Answer:
28.16 °C
Explanation:
Considering that:-
Heat gain by water = Heat lost by metal
Thus,
[tex]m_{water}\times C_{water}\times (T_f-T_i)=-m_{metal}\times C_{metal}\times (T_f-T_i)[/tex]
Where, negative sign signifies heat loss
Or,
[tex]m_{water}\times C_{water}\times (T_f-T_i)=m_{metal}\times C_{metal}\times (T_i-T_f)[/tex]
For water:
Mass = 165 g
Initial temperature = 28 °C
Specific heat of water = 4.184 J/g°C
For metal:
Mass = 4.00 g
Initial temperature = 75 °C
Specific heat of water = 0.600 J/g°C
So,
[tex]165\times 4.184\times (T_f-28)=4.00\times 0.600\times (75-T_f)[/tex]
[tex]690360\left(T_f-28\right)=2400\left(75-T_f\right)[/tex]
[tex]692760T_f=19510080[/tex]
[tex]T_f = 28.16\ ^0C[/tex]
Hence, the final temperature is 28.16 °C
An experiment in chm 2045 requires students to prepare a 1.0 m aqueous solution of potassium phosphate. Jennifer fills a 1.0 liter volumetric flask to the calibration line with water. She then weighs out 212.3 g of potassium phosphate and adds it to the volumetric flask. Joe weighs out 212.3 g of potassium phosphate and adds it to a 1.0 liter volumetric flask. He then fills the volumetric flask to the calibration line with water. Which student has correctly prepared a 1.0 m aqueous solution of potassium phosphate?
Final answer:
Joe correctly prepared the 1.0 M potassium phosphate solution by adding water up to the calibration mark after dissolving the solute, whereas Jennifer's method would result in a concentration less than 1.0 M.
Explanation:
To prepare a 1.0 M aqueous solution of potassium phosphate properly, the student should weigh out the necessary amount of solute and then add it to a volumetric flask that is already partially filled with water. After the solute dissolves, the water should be added to the calibration mark to ensure the correct final volume of the solution. In the scenario described, Joe correctly prepared the solution because he added water to the calibration line after dissolving the potassium phosphate. If Jennifer filled the flask to the calibration mark before adding the solute, her solution would have a slightly greater volume than 1.0 liter, which would result in a concentration of less than 1.0 M. It’s crucial to follow these steps to ensure the solution’s concentration matches the intended molarity.
how many pairs of electrons do two atoms of oxygen need to share to produce one molecule of O2?
Answer:
2 pairs or 4
Explanation:
Oxygen atom belongs to the group 16 of the periodic table also known as the chalcogen group. Oxygen has atomic number of 8. This means it has 8 protons. Hence, for an electrically neutral oxygen atoms, there are 8 electrons.
These electrons are present in the first two shells. There are two electrons in the first shell also known as the K shell. There are 6 electrons in the valence shell of the oxygen atom which is also the L shell. These six valence electrons are the ones responsible for the chemical bonding with other elements.
As said earlier, oxygen atom has six electrons in its valence shell. This means to complete an octet configuration, there are two more electrons needed for it to achieve the needed stability. These two electrons can be obtained ionically or covalently. This depends on the other atom with which it is entering chemical combination with.
In the case of this question, we know it is another oxygen atom. This means each of these atoms will contribute 2 each to make up 2 pairs or 4 electrons which are then controlled by the nuclei of both atoms
An ate or ite at the end of a compound name usually indicates that the compound contains___________.
a. fewer electrons than protons
b. only two elements
c. neutral molecules
d. a polyatomic anion
Answer:
The correct answer is option d. a polyatomic anion.
Explanation:
Hello! Let's solve this!
The ending "ate" or "ite" indicates that there is a negative polyatomic ion (polyatomic anion). This means that the termination of the name will indicate the valence number of the element, if the number used is the highest or the lowest.
An example is:
CO-3: is the carbonate ion
SO-4: is the sulfate ion
We conclude that the correct answer is option d. a polyatomic anion.
An ate or ite suffix at the end of a compound name usually indicates that the compound is a polyatomic anions.
Polyatomic ion:
The ions that contain more than one type of atom. Most of polyatomic ions are anions that are named with suffix -ate or -ite.
For examples-
[tex]\bold {CO_3^-^2}[/tex]- Carbonate ion, end with -ate.
[tex]\bold {SO_3^-^2}[/tex] Sulfite ion, end with -ite.
Therefore, an ate or ite suffix at the end of a compound name usually indicates that the compound is a polyatomic anions.
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A shopkeeper has a few bottles of soft drinks in his shop.But,these are not labelled.He has to serve the drinks on the demand on customers.One customer wants acidic drinks;another wants basic drinks.How will he decide which drink is to be served to whom?
Answer:
He will decide which drink is to be served to whom, by the use of litmus paper.
Explanation:
The litmus paper is the most common indicator to determine the acidity or basicity of a solution. Blue litmus paper changes its color to red when a solution changes from basic to acidic while red litmus paper changes its color to blue when the opposite occurs (acid → basic).
First of all the litmus paper strip, pH indicator, is immersed in a solution and allowed to pass between 10 and 15 seconds while keeping the strip submerged. Afterwards it is removed, and then the strip compares the color. If the color is diffuse, there is a color scale where it is determined which solution has alkaline or acidic pH
Consider the voltaic cellZn(s) + Cu{2+}(aq)--> Zn{2+}(aq)+Cu(s){}=chargeUnder standard conditions, what is the maximum electrical work, in Joules that can accomplish if 60 g of copper is plated out?
Answer:
Max. work done in 60 g of copper plated out is 200472.14 J
Explanation:
Given cell reaction is:
[tex]Zn(s)+Cu^{2+} \rightarrow Zn^{2+}+Cu(s)[/tex]
Standard reduction potential of Zn electrode ([tex]E_{Zn^{2+}/Zn}[/tex]) is 0.763 V.
Standard reduction potential of Cu electrode ([tex]E_{Cu^{2+}/Cu}[/tex]) is -0.337 V.
Copper acts as cathode and Zinc acts as anode.
Cell potential (E) = E° cathode - E° anode
= 0.763 - (-0.337)
= 1.10 V
formula for the work done is as follows:
[tex]W_{max}=-nFE[/tex]
Here, n is no. of electron involved in the reaction.
F(Faraday's constant) = 96500
In the given reaction, n = 2
[tex]W_{max}=-nFE\\=-2 \times\ 96500 \times 1.10\\=-212300\ J/mol[/tex]
Therefore, 212300 J work is done by reducting 1 mol of copper.
Copper given is 60 g.
Molecular mass of copper is 63.54 g/mol.
[tex]No.\ of\ mol = \frac{60\ g}{63.54\ g/mol}[/tex]
Max. work done in 60 g of copper plated out is:
[tex]W_{max}=212300\ J/mol \times \frac{60\ g}{63.54\ g/mol} \\=200472.14\ J[/tex]
Miles mixed two unlabeled solutions together. This caused a bad reaction, and a noxious gas was emitted. Which describes what Miles should do?
A. He should use a fire blanket to cover his solutions.
B. He should report the accident and leave the area.
C. He should neutralize the reaction by adding water.
D. He should pour the solution down the sink to stop the gas.
Answer:
B. He should report the accident and leave the area.
Explanation:
Noxious gases are harmful and might cause hallucination or even death. Examples of such gases carbon monoxide (CO) and Ammonia gas (NH3).
Let's look at all the options
All the solutions except for B is increasing his time of contact with the gas. This will increase his exposure and might cause death. The fire blanked in option A is used to cover the fire and NOT the gas. It’s simply not made for it. Also, the blanket material might react with the gas to create additional fumes. He should not neutralize it with water as the solution might contain a group 1 metal e.g. Na (sodium). In that case the container will explode and hydrogen gas will release. Pouring the solution down the sink won’t stop the gas as the reaction has occurred already. It will only make the situation worse as after pouring the mixture, the gas will get more space to spread across the room.Therefore, He should report the accident and leave the area.
Answer:
b
Explanation:
A. mine functional groups are fully protonated, and can be described with the chemical formula: N+H3.
B. Caboxylic acid functional groups are deprotonated, and can be described with the chemical formula: COO-.
C. Amine functional groups are positively charged.
D. Amine functional groups are fully protonated, and can be described with the chemical formula: NH2.
E. Carboxylic acid functional groups are positively charged.
F. Caboxylic acid functional groups are fully protonated, and can be described with the chemical formula: COOH.
Answer:
The correct statements are A amine groups are fully protonated and can be described with the chemical formula NH3+ B carboxylic acid functional groups are de protonated and can be be described with the chemical formula COO- C Amine functional groups are positively.
Explanation:
If we study the biochemical structure of an amino acid we wil see that an amino group or -NH2 is present at one end and a carboxylic group or COOH is present at another end.
Now the fact the that when an amino acid exist as zwitterion it contain same number of positive charge as well as same number of negative charge.So during zwitterion formation the carboxylic acid or -COOH liberates a proton and exist as COO- whereas the amine group accepts that proton and exist as NH3+.
Beside this the amine group -NH2 after the formation of zwitterion gains a positive charge and exist as -NH3+.
in example 5.11 of the text the molar volume of n2 at STP is given as 22.42 L/mol how is this number calculatd how does the molar volume of h2 at stp compare th te molar volume of n2
Answer:
V = 22.42 L/mol
N₂ and H₂ Same molar Volume at STP
Explanation:
Data Given:
molar volume of N₂ at STP = 22.42 L/mol
Calculation of molar volume of N₂ at STP = ?
Comparison of molar volume of H₂ and N₂ = ?
Solution:
Molar Volume of Gas:
The volume occupied by 1 mole of any gas at standard temperature and pressure and it is always equal to 22.42 L/ mol
Molar volume can be calculated by using ideal gas formula
PV = nRT
Rearrange the equation for Volume
V = nRT / P . . . . . . . . . (1)
where
P = pressure
V = Volume
T= Temperature
n = Number of moles
R = ideal gas constant
Standard values
P = 1 atm
T = 273 K
n = 1 mole
R = 0.08206 L.atm / mol. K
Now put the value in formula (1) to calculate volume for 1 mole of N₂
V = 1 x 273 K x 0.08206 L.atm / mol. K / 1 atm
V = 22.42 L/mol
Now if we look for the above calculation it will be the same for H₂ or any gas. so if we compare the molar volume of 1 mole N₂ and H₂ it will be the same at STP.
In chemistry, what varies with the number of molecules present in a sample of a particular substance?
Answer: concentration
Explanation:
Concentration refers to the amount of a substance present in a sample. The more molecules of a substance present in a sample, the greater its concentration. The less molecules of a substance in a sample, the lesser the concentration. We are often concerned about analytically determining the concentration of a substance using diverse analytical methods in chemistry.
A lithium salt used in lubricating grease has the formula LiCnH2n+1O2. The salt is soluble in water to the extent of 0.036 g per 100 g of water at 25 ∘C. The osmotic pressure of this solution is found to be 57.1 torr. Assuming that molality and molarity in such a dilute solution are the same and that the lithium salt is completely dissociated in the solution, determine an appropriate value of n in the formula for the salt.
Answer:
The value of n is 14.
Explanation:
To calculate the concentration of solute, we use the equation for osmotic pressure, which is:
[tex]\pi=icRT[/tex]
where,
[tex]\pi[/tex] = osmotic pressure of the solution = 57.1 Torr =[tex]\frac{57.1}{760} atm = 0.07513 atm[/tex]
1 atm = 760 Torr
i = Van't hoff factor = 2 (electrolytes)
c = concentration of solute = ?
R = Gas constant = [tex]0.0820\text{ L atm }mol^{-1}K^{-1}[/tex]
T = temperature of the solution = [tex]25^oC=[273.15+25]=298.15 K[/tex]
Putting values in above equation, we get:
[tex]c=\frac{\pi}{iRT}=\frac{0.07513 atm}{2\times 0.0821 atm L/mol K\times 298.15 K}[/tex]
[tex]c=0.001535 mol/L[/tex]
Assuming that molality and molarity in such a dilute solution.
c = m (Molality)
The salt is soluble in water to the extent of 0.036 g per 100 g of water at 25°C
[tex]Molaity=\frac{\text{Mass of solute}}{\text{molar mass of solute(M)}\times \text{Mass of solvent in kg}}[/tex]
Molality of the solution = m = 0.001535 mol/L
[tex]\frac{0.036 g}{M\times 0.1 kg}=0.001535 mol/kg[/tex]
M = 234.53 g/mol
Molar mass of [tex]LiC_nH_{2n+1}O_2[/tex] : M
M = [tex]7 g/mol\times 1 + 12 g/mol \times n +1 g/mol\times (2n+1)+2\times 16 g/mol[/tex]
[tex]234.53 g/mol=7 g/mol\times 1 + 12 g/mol \times n +1 g/mol\times (2n+1)+2\times 16 g/mol[/tex]
n = 14
The value of n is 14.
Final answer:
To find the value of n in LiCnH2n+1O2, the osmotic pressure and solubility data were used, assuming complete dissociation. However, the van 't Hoff factor may be less than the ideal value due to high lattice energy of lithium compounds, leading to potential incomplete dissociation. Further experiments or calculations are necessary to accurately determine n.
Explanation:
To determine an appropriate value of n in the formula LiCnH2n+1O2 for the lithium salt used in lubricating grease, we will use the osmotic pressure measurement given and the assumption of complete dissociation. Given that the osmotic pressure is 57.1 torr, which converts to 0.075 atm (since 1 atm = 760 torr), we can use the formula for osmotic pressure Π = iMRT, where Π is the osmotic pressure in atmospheres, i is the van 't Hoff factor, M is the molarity, R is the ideal gas constant (0.0821 L⋅atm/mol⋅K), and T is the temperature in Kelvin (298 K, assuming 25°C room temperature). In this case, the salt fully dissociates into Li+ and the organic anion, hence the van 't Hoff factor, i, should be 2.
First, we determine the molarity of the solution. We have a solubility of 0.036 g per 100 g of water, which equates to 0.036 g in 0.1 kg of water. Assuming an approximate molar mass for the lithium salt to be around 6 (Li) + 14n (for the CnH2n+1 part) + 32 (for O2) = 38 + 14n, we can use the relation:
Π = (2)(M)(0.0821)(298)
0.075 atm = (2)(M)(0.0821)(298)
By isolating M, we find M = 0.075 / (2 * 0.0821 * 298) = 0.001538 mol/kg. Given the weight of the salt used, we can calculate the molar mass: 0.036g / 0.001538 mol/kg = 23.41 g/mol. Using the approximate molar mass 38 + 14n = 23.41, we can solve for n:
38 + 14n = 23.41
14n = -14.59
n ≈ -1.04
However, since n cannot be negative and must be an integer for an organic molecule, an error must have occured in our calculations or assumptions. Lithium compounds do have high lattice energies, and hence it's possible that the ionic compound doesn't fully dissociate.
Considering the information provided about Lithium compounds, lattice energy, and real solutions being less than ideal, the van 't Hoff factor i for the lithium salt may actually be less than the ideal value of 2, indicating incomplete dissociation. Additional experiments or refined calculations would be required to determine the actual value of n.
In the process of ionic bonding:__________ a. outer energy level electrons are shared b. the resulting molecule is always charged c. outer energy level electrons are gained and lost d. the resulting ions repel each other
A. Outer energy level electrons are shared.
In electrovalent combination, after donating their valence electrons, metallic particles become positively charged; non metallic particles become negatively charged after acquiring extra electrons.
The electrons involved reside in the outermost shells of the atoms.
PeAcE.
There are two types of chemical compound one is covalent compound and other is ionic compound in chemistry, covalent compound formed by sharing of electron and ionic compound formed by complete transfer of electron. The correct option is option A
What is chemical Compound?Chemical Compound is a combination of molecule, Molecule forms by combination of element and element forms by combination of atoms in fixed proportion. Ionic compound are very hard, they have very high melting and boiling point.
There is complete transfer of electron from one element to another from from the outer energy levels of element. Only the electrons that are present in the outermost shell are ready to react, only these electrons participte in the reaction
Therefore the correct option is option A
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The vapor pressure of water at 25 degrees Celsius is 23.8 torr, and the heat of vaporization of water at 25 degrees Celsius is 43.9 kJ/mol. Calculate the vapor pressure of water at 50 degrees Celsius.
Answer:
The vapor pressure of water at 50 °C is 93.7 torr.
Explanation:
The expression for Clausius-Clapeyron Equation is shown below as:
[tex]\ln P = \dfrac{-\Delta{H_{vap}}}{RT} + c [/tex]
Where,
P is the vapor pressure
ΔHvap is the Enthalpy of Vaporization
R is the gas constant (8.314×10⁻³ kJ /mol K)
c is the constant.
For two situations and phases, the equation becomes:
[tex]\ln \left( \dfrac{P_1}{P_2} \right) = \dfrac{\Delta H_{vap}}{R} \left( \dfrac{1}{T_2}- \dfrac{1}{T_1} \right)[/tex]
Given:
[tex]P_1[/tex] = 23.8 torr
[tex]P_2[/tex] = ?
[tex]T_1[/tex] = 25°C
[tex]T_2[/tex] = 50 °C
ΔHvap = 43.9 kJ/mol
The conversion of T( °C) to T(K) is shown below:
T(K) = T( °C) + 273.15
So,
T = (25 + 273.15) K = 298.15 K
T = (50 + 273.15) K = 323.15 K
[tex]T_1[/tex] = 298.15 K
[tex]T_2[/tex] = 323.15 K
So, applying in the above equation as:-
[tex]\ln \:\left(\:\frac{23.8}{P_2}\right)\:=\:\frac{43.9}{8.314\times 10^{-3}}\:\left(\:\frac{1}{323.15}-\:\frac{1}{298.15}\:\right)[/tex]
[tex]\frac{23.8}{P_2}=e^{\frac{43.9}{8.314\times \:10^{-3}}\left(\frac{1}{323.15}-\frac{1}{298.15}\right)}[/tex]
[tex]23.8=\frac{1}{e^{\frac{1097500}{801030.39216}}}P_2[/tex]
[tex]P_2=23.8e^{\frac{1097500}{801030.39216}}=93.7\ torr[/tex]
The vapor pressure of water at 50 °C is 93.7 torr.
To calculate the vapor pressure of water at a different temperature, you can use the Clausius-Clapeyron equation, which relates the vapor pressure of a liquid to its temperature. Input the known values into the equation, and solve for the vapor pressure at the new temperature.
Explanation:The key to answering this question is the Clausius-Clapeyron relationship, an equation used in Physical Chemistry to describe the relationship between the vapor pressure and temperature of a liquid. The equation is { ln(P2/P1) = -ΔHvap/R (1/T2 - 1/T1) }. Where P1, T1 represent the initial condition, in this case, the vapor pressure at 25 degrees Celsius (converted to Kelvin - 298.15 K) and seed pressure; P2 and T2 represent the final conditions, P2 being the one we want to calculate and T2 the final temperature (50 degrees Celsius converted to Kelvin - 323.15 K); ΔHvap is the enthalpy of vaporization, and R is the ideal gas constant (8.314 J/mol*K). Solve the equation for P2 to find the final vapor pressure under the new conditions.
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Calculate the value of K p for the equation C ( s ) + CO 2 ( g ) − ⇀ ↽ − 2 CO ( g ) K p = ? given that at a certain temperature C ( s ) + 2 H 2 O ( g ) − ⇀ ↽ − CO 2 ( g ) + 2 H 2 ( g ) K p 1 = 3.79 a t m H 2 ( g ) + CO 2 ( g ) − ⇀ ↽ − H 2 O ( g ) + CO ( g ) K p 2 = 0.601
Answer:
Kp = 1.37
Explanation:
In order to do this, we need to apply the Hess's law which it states:
"The heat of any reaction ΔHf° for a specific reaction is equal to the sum of the heats of reaction for any set of reactions which in sum are equivalent to the overall reaction"
Now, here we don't have data for enthalpy but we do have Kp, so the principle is applied similarly, even is we have Kp.
First thing we should do is to get the overall reaction needed which is the following:
C(s) + CO2(g) <-----> 2CO(g) (3)
To get to this reaction, we just need to sum the other two reactions, and multiply coefficients if it's needed so:
C(s) + 2H2O(g) <----> CO2(g) + 2H2(g) Kp1 = 3.79 (1)
H2(g) + CO2(g) <----> H2O(g) + CO(g) Kp2 = 0.601 (2)
Now, in order to get equation (3), let's look at equations 1 and 2. As we can see, in both equations we have molecules of H2 and water, which aren't present in the overall reaction 3, so we need to get rid of them. In order to do so, if look carefully, you'll see that if you substract molecule of H2 from 1 and from 2, you still have traces of H2 (Because 2H2 - H2 = H2), so, how can we equal both of the molecules?.
That's right, we need to multiply the coefficient of that molecule to equal the coefficient of reaction 1. However keep in mind, that doing so, it will multiply the coefficients of the other molecules too. So doing that we have:
2H2(g) + 2CO2(g) <----> 2H2O(g) + 2CO(g) Kp = (0.601)²
Now, by multiplying the coefficients of the reaction, it also affects the value of Kp; remember that Kp is a value that you can obtain by doing this:
Kp = P(products) / P(reactants)
If we modify the coefficients by two, Kp is altered:
Kp = P(prod)² / P(react)²
That is why we elevated the value of Kp. Now, summing both equation 2 and 4 we have:
C(s) + 2H2O(g) <----> CO2(g) + 2H2(g) Kp1 = 3.79
2H2(g) + 2CO2(g) <----> 2H2O(g) + 2CO(g) Kp = (0.601)²
______________________________________________
C(s) + CO2(g) <-----> 2CO(g) (3)
Now the value of Kp will be:
Kp = 3.79 x (0.601)² = 1.37
In this exercise we have to calculate the value of the constant, like this:
Kp = 1.37
Using the Hess formula and knowing the equation given as:
[tex]C(s) + CO2(g) \rightarrow 2CO(g)[/tex]
To get to this reaction, we just need to sum the other two reactions, and multiply coefficients if it's needed so:
[tex]C(s) + 2H2O(g) \rightarrow CO2(g) + 2H2(g) \ Kp_1 = 3.79 \\H2(g) + CO2(g) \rightarrow H2O(g) + CO(g) \ Kp_2 = 0.601[/tex]
Multiply the coefficients of the other molecules, we have that:
[tex]2H_2(g) + 2CO_2(g) \rightarrow 2H_2O(g) + 2CO(g) \ Kp = (0.601)^2[/tex]
To find the value of the constant we have to use the formula below and put the values already :
[tex]Kp = P(products) / P(reactants)\\Kp = P(prod)^2 / P(react)^2\\Kp_1 = 3.79\\Kp_2 = (0.601)^2\\Kp = 3.79 * (0.601)^2 = 1.37[/tex]
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The elephant toothpaste demonstration was a great example of the use of potassium iodide as "catalyst". Why did Dr. Hartings use potassium iodide in this demonstration?
To slow down the reaction
To speed up the reaction
To preserve the oxygen in the soap bubbles
To give color to the foam
Ammonia is one of the most produced chemical compounds in the world today. Which of the following is the main real-world use for ammonia? *
2 points
To maintain the level of of nitrogen in the air (78%)
To produce household cleaners
To produce nitric acid
To produce fertilizer for crops
Answer: To speed up the reaction
Explanation:
Potassium iodide is used in elephant toothpaste reaction for the decomposition of hydrogen peroxide by removal of oxygen from the solution ,so that reaction gets completed. Potassium iodide is the catalyst and we know that the concentration of catalyst will not change throughout the reaction so, Potassium iodide will not be consumed in the foam making process.
What substances that are formed by the chemical combination of two or more elements in definite proportions
Answer:
This are called compounds
Explanation:
Compounds are substances formed when two or more elements are combined, and by definite proportions they should always be in fixed ratios. The elements can be bonded together either through covalent or ionic bonding.
In a covalent bond the atoms in the compound are sharing their outermost electrons to achieve stability, for example, CF4, CH4, CH3COOH among others. Most of the organic compounds are made of covalent bonds.
In an Ionic bond atoms in the compound are losing and gaining each others' valence electron (transfer of electrons) to form and achieve stability. For example, NaCl, KOH, CaBr2, among others. Inorganic compounds are in their majorities, ionic compounds.
We also can have metallic bonds.
Compounds are formed by the chemical combination of two or more elements in fixed proportions and have unique properties. There can be millions of compounds formed from combinations of elements, each with distinct properties. Compounds differ from mixtures, which can vary in composition.
Explanation:Substances that are formed by the chemical combination of two or more elements in definite proportions are known as compounds. These compounds are formed when elements are chemically bonded together. For example, water is a compound that is made up of hydrogen and oxygen in a 2:1 ratio.
An interesting point here is that even though there are just over 100 known elements, there are tens of millions of chemical compounds resulting from various combinations of these elements. Each of these compounds has a unique composition and distinct chemical and physical properties that set it apart from all other compounds.
It's also essential to distinguish compounds from mixtures. Unlike compounds, mixtures contain two or more substances that are not chemically bonded together and can be separated by physical means. The composition of a mixture can vary, while the composition of a compound is always fixed.
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A certain amount of H2S was added to a 2.0 L flask and allowed to come to equilibrium. At equilibrium, 0.072 mol of H2 was found. How many moles of H2S were originally added to the flask?
Answer:
0.098 moles H₂S
Explanation:
The reaction that takes place is
2H₂(g) + S₂(g) ⇄ 2H₂S(g) keq = 7.5We can express the equilibrium constant as:
keq = [H₂S]² / [S₂] [H₂]² = 7.5With the volume we can calculate the equilibrium concentration of H₂:
[H₂] = 0.072 mol / 2.0 L = 0.036 MThe stoichiometric ratio tells us that the concentration of S₂ is half of the concentration of H₂:
[S₂] = [H₂] / 2 = 0.036 M / 2 = 0.018 MNow we can calculate [H₂S]:
7.5 = [H₂S]² / (0.018*0.036²)[H₂S] = 0.013 MSo 0.013 M is the concentration of H₂S at equilibrium.
This would amount to (0.013 M * 2.0 L) 0.026 moles of H₂SThe moles of H₂ at equilibrium are equal to the moles of H₂S that reacted.Initial moles of H₂S - Moles of H₂S that reacted into H₂ = Moles of H₂S at equilibrium
Initial moles of H₂S - 0.072 mol = 0.026 mol
Initial moles of H₂S = 0.098 moles H₂S
The number of moles of H2S initially added to the flask is 0.036 mol, calculated based on the number of moles of H2 gas (0.072 mol) obtained at equilibrium by assuming that each mole of H2S gives two moles of H2.
Explanation:This question deals with the concept of chemical equilibrium in the reaction of hydrogen sulfide gas (H2S). It's assumed in the question that H2S gas dissociates into H2 and S2 according to the equation: H2S(g) ⇌ 2H2(g) + S2(g). When 0.072 mol of H2 is obtained at equilibrium, it implies that each mole of H2S gives two moles of H2. Therefore, the number of moles of H2S that were originally added to the flask would be half of the moles of H2 obtained at the equilibrium. Hence, the moles of H2S originally added to the flask are 0.072 / 2 = 0.036 mol.
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Which of the following correctly describes the orbital hybridization of XeF4 and NH3, respectively?A. sp3d2, sp3B. sp3, sp3C. sp3, sp2D. sp3d2, sp2
Answer:
A
Explanation:
Hybridization is simply a phenomena which involves the mixing of orbitals to form new ones. It is simply a way of forming a whole new set of orbitals from old ones.
In XeF4, the type of hybridization that we have is the sp3d2 hybridization. This simply means we have one s orbital, mixing with 3 p orbitals and 2 d orbitals. These orbitals mix together to form the new hybrid orbital. It must be noted that the hybridization takes place in the central atom xenon Xe. The valence shell of xenon contains 2 electrons in the 5s orbital and 6 electrons in the 5p orbitals. In the state of excitement, 2 of the electrons in the outermost 5p orbitals get excited and promoted to the 5d orbitals. This causes a total of four unpaired electrons in which the four chlorine atom can attach with.
In ammonia, there are three hydrogen atoms which seek to join forces with a single nitrogen atom. It must be known that there are 8 electrons around the central atom nitrogen. There are a set of lone pair which are non bonding while the other three are in connection with the 3 hydrogen atoms. Instead of the molecule having 1s and 3p orbitals, they show hybridization to give sp3 hybrid orbital
Compared to the physical and chemical properties of the compound NO2, the compound N2O has
A. the same physical properties and the same chemical properties
B. different physical properties and different chemical properties
C. different physical properties and the same chemical properties
D. the same physical properties and different chemical properties
Answer:
B
Explanation:
The two compounds have different physical properties and different chemical properties despite the fact that they are formed from nitrogen and oxygen.
The compounds NO2 and N2O have different physical and chemical properties due to their varied molecular structures and resulting behaviors in both physical states and chemical reactions.
Explanation:Compared to the physical and chemical properties of the compound NO2, the compound N2O has different physical properties and different chemical properties. This is because even though both compounds consist of nitrogen and oxygen, they have different molecular structures, which results in differences in their physical properties such as color, phase at room temperature, and boiling points. Similarly, their chemical properties also differ, such as their reactivity with other chemicals and their role in various chemical reactions.
For instance, NO2 is a reddish-brown gas that is a significant air pollutant, whereas N2O, commonly known as laughing gas, is a colorless gas and used as an anesthetic in dentistry. The correct answer to the student's question is therefore option B: different physical properties and different chemical properties.
The National Weather Service routinely supplies atmospheric pressure data to help pilots set their altimeters. The units the NWS uses for atmospheric pressure are inches of mercury. A barometric pressure of 30.51 inches of mercury corresponds to __________ kPa.
a. 77.50
b. 775.0
c. 1.020
d. 103.3
e. 16.01
Answer:
d. 103.3
Explanation:
In the given question, the National Weather Service routinely supplies atmospheric pressure data to help pilots set their altimeters. And the units of atmospheric pressure used for reporting the atmospheric pressure data are inches of mercury. For a barometric pressure of 30.51 inches of mercury, we can calculate the pressure in kPa as follow:
In principle, 3.386 kPa is equivalent to the atmospheric pressure of 1 inch of mercury. Thus, 30.51 inches of mercury is equivalent to 30.51 in *(3.386 kPa/1 in) = 103.307 kPa.
Therefore, a barometric pressure of 30.51 inches of mercury corresponds to _____103.3_____ kPa.
IF an Axonal Membrane transiently becomes very permeable to Na+ ions then the membrane potential of the cell wall will approach:a. (+)132 mVb. (+)50 mVc. (-)60 mVd. (+)70 mVe. (-)94 mV
Answer:
The correct option is D ((+)70 mV)
Explanation:
IF an Axonal Membrane transiently becomes very permeable to Na+ ions then the membrane potential of the cell wall will approach (+)70 mV.
Based on the graph, how would you BEST describe the speed of the racehorse?
A) constantly decreasing speed
B) both increasing and decreasing speed
C) stopped, starting, and then stopped again
D) starting to move and then increasing speed
Answer:
The correct option is:
D) starting to move and then increasing speed
Explanation:
The speed of the racehorse is given by the slope of the given Distance-time graph.
Speed = Distance/time = Slope of the graph
The slope of the graph keeps increasing.
Hence, the speed of the racehore is increasing.
The distance moved is zero at t=0. Hence, the racehorse has started to move from rest.
Answer:
D
Explanation:
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If 200. mL of 0.60 M MgCl2(aq) is added to 400. mL of distilled water, what is the concentration of Mg2+(aq) in the resulting solution? (Assume volumes are additive).
Answer:
Final concentration of Mg2+ = 0.20 M
Explanation:
Concentration of [tex]MgCl_2(aq)\ (M_1)[/tex] = 0.60 M
Volume of [tex]MgCl_2(aq)\ (V_1)[/tex] = 200 mL
Volume of distilled water added = 400 mL
Final volume of the soution = 200 mL + 400 mL
= 600 mL
Final concentration of solution = [tex]M_2[/tex]
The final concentration is calculated as follows:
[tex]M_1 V_1=M_2V_2\\0.60 \times 200= M_2 \times 600\\M_2=\frac{0.60\times 200}{600} =0.20\ M[/tex]
Therefore, final concentration of the solution is 0.20 M.
[tex]MgCl_2(aq)[/tex] exists in the solution as Mg2+ and 2Cl-.
Therefore, concentration of Mg2+ is same as the final concentration of solution.
Final concentration of Mg2+ = 0.20 M
The concentration of magnesium ion, Mg²⁺ in the resulting solution is 0.2 M.
To solve this question, we'll begin by calculating the molarity of the diluted solution. This can be obtained as follow:
Volume of stock solution (V₁) = 200 mL
Molarity of stock solution (M₁) = 0.60 M
Volume of diluted solution (V₂) = 200 + 400 = 600 mL
Molarity of diluted solution (M₂) = ?The molarity of the diluted solution can be obtained as follow:
M₁V₁ = M₂V₂
0.6 × 200 = M₂ × 600
120 = M₂ × 600
Divide both side by 600
M₂ = 120 / 600
M₂ = 0.2 MThus, the molarity of the diluted solution of MgCl₂ is 0.2 M
Finally, we shall determine the concentration of Mg²⁺ in the diluted solution. This is illustrated below:
MgCl₂(aq) —> Mg²⁺(aq) + 2Cl¯(aq)
From the balanced equation above,
1 mole MgCl₂ dissolves to produce 1 mole Mg²⁺.
Therefore,
0.2 M MgCl₂ will also produce 0.2 M Mg²⁺.
Thus, the concentration of Mg²⁺ in the resulting solution is 0.2 M.
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Tyrel is learning about a certain kind of metal used to make satellites. He learns that infrared light is absorbed by the metal, X-ray light is transmitted through the metal, and visible light is reflected off the metal. Tyrel wonders if the metal will get warm if he shines the lights on it. Can light cause the metal to get warm? Why or why not? Does it matter what type of light shines on the metal?
Answer:
Below.
Explanation:
Light will make the metal warmer because it isn't a perfect reflector. Some of the photons from the light are absorbed by the metal.
I think infrared light will make it warmer than visible light.
Light has been the form of energy that has been emitted in the form of photons. The shining of the light onto the metal body will warm up the metal as the part of incident radiation has been absorbed by the metal.
A black body is one that reflects all the radiation that is incident onto it. The metal is not a perfect black body. Since the metal has not been emitting all the radiations, the radiations have been absorbed by the metal.
The absorption of the radiations by the metal will provide energy that results in the metal turning warm.
The varying type of light will have varying intensity and energy. Thus the varying light will result in the difference in the warming of the metal.
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Which molecule would you expect to be more soluble in water, CH3CH2CH2OH or HOCH2CH2CH2OH? Explain.
Answer:
HOCH2CH2CH2OH.
Explanation:
HOCH2CH2CH2OH is more soluble in water than CH3CH2CH2OH because propandiol have two alcoholic group attached to it hence, it can form more efficient hydrogen bonding with water whereas the hydrogen bonding in CH3CH2CH2OH would be less prominent as it has only one alcoholic group.
Answer:
HOCH2CH2CH2OH
Consider a hypothetical experiment in which the left beaker contains 4 mM NaCl, 9 mM glucose and 10 mM albumin. The right beaker contains 10 mM NaCl, 10 mM glucose and 40 mM albumin. The dialysis membrane is permeable to all substances except albumin. In which direction will glucose move?
Answer:
to the left beaker
Explanation:
In the system above, we have two beakers containing different concentrations of glucose. In addition, the two beakers are separated by a permeable membrane which can allow the movement of glucose from one beaker to another. In order to attain equilibrium conditions, there will be a movement of glucose from the beaker with high glucose concentration (right beaker) to the beaker with low glucose concentration (left beaker).
How many seconds are required to produce 4.00 g of aluminum metal from the electrolysis of molten alcl3 with an electrical current of 12.0 a?
Answer: 3618 seconds
Explanation:
[tex]\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}=\frac{4g}{27g/mol}=0.15moles[/tex]
According to mole concept:
1 mole of an atom contains [tex]6.022\times 10^{23}[/tex] number of particles.
We know that:
Charge on 1 electron = [tex]1.6\times 10^{-19}C[/tex]
Charge on 1 mole of electrons = [tex]1.6\times 10^{-19}\times 6.022\times 10^{23}=96500C[/tex]
[tex]AlCl_3\rightarrow Al^{3+}+3Cl^-[/tex]
At cathode: [tex] Al^{3+}+3e^-\rightarrow Al[/tex]
1 mole of aluminium is deposited by = [tex]3\times 96500=289500C[/tex]
Thus 0.15 moles of aluminium is deposited by = [tex]\frac{289500C}{1}\times 0.15=43425C[/tex]
To calculate the time required, we use the equation:
[tex]I=\frac{q}{t}[/tex]
where,
I = current passed =12.0 A
q = total charge = [tex]43425C[/tex]
t = time required in seconds = ?
Putting values in above equation, we get:
[tex]12.0A=\frac{43425C}{t}\\\\t=\frac{43425C}{12.0A}=3618s[/tex]
Hence, the amount of time required to produce 4.00 g of aluminum metal from the electrolysis of molten [tex]AlCl_3[/tex] with an electrical current of 12.0 A is 3618 seconds
A cylinder with a movable piston contains a fixed amount of gas at a constant pressure. Initially, the cylinder contains 0.25 liters of air at 0 degrees Celsius. When the temperature is increased to 35 degrees Celsius, the air will occupy what volume?
a. 0.28 L
b. 0.88 L
c. 8.75 L
d. 35.25 L
Answer:
a. 0.28 L
Explanation:
At constant pressure and number of moles, Using Charle's law
[tex]\frac {V_1}{T_1}=\frac {V_2}{T_2}[/tex]
Given ,
V₁ = 0.25 L
V₂ = ?
T₁ = 0 °C
T₂ = 35 °C
The conversion of T( °C) to T(K) is shown below:
T(K) = T( °C) + 273.15
So,
T₁ = (0 + 273.15) K = 273.15 K
T₂ = (35 + 273.15) K = 308.15 K
Using above equation as:
[tex]\frac{0.25}{273.15}=\frac{V_2}{308.15}[/tex]
[tex]V_2=\frac{0.25\cdot \:308.15}{273.15}[/tex]
New volume = 0.28 L
Which type of drum is used for the storage of corrosives such as acids, bases, or oxidizers?
Answer:
Polyethylene Drums
Explanation:
Drums are recognisable barrel-like containers. they are used to store a wide variety of substances, including food-grade materials, corrosive flammable liquids and grease
Drums may be constructed of low-carbon steel, polyethylene and cardboard.
Generally the nature of the chemical dictates the construction of the drum
Polyethylene drums are use for storage of corrosive chemicals such as acid bases, or oxidizers and other materials that cannot be stored in steel containers, because of their chemical structure .
When one atom losses an electron and another atom simultaneously gains one, what has taken place is called _____.
Answer:
Ionic bond
Explanation:
Ionic bonding:-
This type of bonding is formed when there is a complete transfer of electrons from one element to another element. In this bonding one element is always a metal and another is a non-metal.
Thus, the atom which loses the electron which is gained by the another, there is a electrostatic attraction between two which which results in the formation of ionic bond.
For example:-
Calcium is the element of second group and forth period. The electronic configuration of Calcium is - 2, 8, 8, 2 or [tex]1s^22s^22p^63s^23p^64s^2[/tex]
There are 2 valence electrons of Calcium.
Sulfur is the element of sixteenth group and third period. The electronic configuration of sulfur is - 2, 8, 6 or [tex]1s^22s^22p^63s^23p^4[/tex]
There are 6 valence electrons of sulfur.
Thus, calcium loses two electrons to sulfur and sulfur accepts these electrons to form ionic bond.
Calcium sulfide, [tex]CaS[/tex] is formed when 2 valence electrons of calcium are loosed and they are gained by sulfur atom.
Here are some questions about the elements, their properties, and periodicity. In each case. the correct answer is the name of an element (one of the two given). Write the answer in the appropriate space at right, placing the first letter in the first blank. There are more than enough blanks to fit either element name, so the number of letters in the name cannot be used as a clue. When the puzzle is complete, the Periodic Law will be displayed in the shaded column. Record the Periodic Law at the bottom of the page.
Answer: Please provide more details of the elements to help answer the question
Explanation: