Answer:- 6.91 kj of heat is needed.
Solution:- We have solid ethanol at -135 degree C and wants to calculate the heat required to convert it to -50 degree C liquid ethanol.
Melting point of ethanol is -114 degree C. So, it is a three step process. In the first step, -135 degree C solid ethanol changes to -114 degree C solid ethanol.
In second step, -114 degree C solid ethanol melts to -114 degree C liquid ethanol. In third step, -114 degree C liquid changes to -50 degree C liquid.
for the first and third step, there is a change in temperature and so we use the equation, [tex]Q=ms\Delta T[/tex]
where, Q is the heat energy, m is mass in grams, s is specific heat capacity in joule per gram per degree C and [tex]\Delta T[/tex] is the change in temperature.
For second step, there is a phase change so the equation used is, [tex]Q=m\Delta H_f_u_s[/tex]
where [tex]\Delta H_f_u_s[/tex] is the enthalpy of fusion.
Let's do the calculations for the first step:-
[tex]\Delta T[/tex] = -114-(-135) = 21 degree C
m = 25.0 g
s = 0.97 J per g per degree C
[tex]Q_1=25.0g(0.97\frac{J}{g.^0C})(21^0C)[/tex]
[tex]Q_1[/tex] = 509.25 J
let's convert this J to kj
[tex]509.25J(\frac{1kj}{1000J})[/tex]
= 0.509 kj
For the second step we need the moles of ethanol as the enthalpy of fusion is given in kj per mol. Molar mass of ethanol is 46.07 g per mol.
[tex]25.0g(\frac{1mol}{46.07g})[/tex]
= 0.543 mol
[tex]Q_2=0.543mol(\frac{5.02kj}{mol})[/tex]
[tex]Q_2[/tex] = 2.72 kj
For the third step, [tex]\Delta T[/tex] = -50 -(-114) = 64 degree C
[tex]Q_3=25.0g(2.3\frac{J}{g.^0C})(64^0C)[/tex]
[tex]Q_3[/tex] = 3680 J
[tex]3680J(\frac{1kj}{1000J})[/tex]
= 3.68 kj
total Q = [tex]Q_1+Q_2+Q_3[/tex]
total Q = 0.509 kj + 2.72 kj + 3.68 kj
total Q = 6.909 kj
this could be round to 6.91 kj.
So, 6.91 kj of heat is needed to convert -135 degree C solid ethanol to -50 degree C ethanol.
Final answer:
To convert 25.0 g of solid ethanol at -135°C to liquid ethanol at -50°C, approximately 9.161 kJ of heat is needed. This involves heating the solid, melting it, and then heating the liquid to the final temperature.
Explanation:
To calculate the heat needed to convert 25.0 g of solid ethanol at -135°C to liquid ethanol at -50°C, three steps are involved:
Calculate the heat required to raise the temperature of solid ethanol from -135°C to its melting point at -114°C.
Calculate the heat absorbed when solid ethanol melts at -114°C.
Calculate the heat required to raise the temperature of liquid ethanol from -114°C to -50°C.
Using the specific heat of solid ethanol (0.97 J/g·K) for the first part:
q1 = mass x specific_heat_solid x ∆T_solid = 25.0 g x 0.97 J/g·K x (114 K) = 2763 J or 2.763 kJ
For the phase change at the melting point:
q2 = moles x enthalpy_fusion = (25.0 g / 46.07 g/mol) x 5.02 kJ/mol = 2.718 kJ
Finally, for the temperature increase of the liquid phase, using its specific heat:
q3 = mass x specific_heat_liquid x ∆T_liquid = 25.0 g x 2.3 J/g·K x (64 K) = 3680 J or 3.680 kJ
The total heat (q_total) is the sum of q1, q2, and q3:
q_total = q1 + q2 + q3 = 2.763 kJ + 2.718 kJ + 3.680 kJ = 9.161 kJ
So, approximately 9.161 kJ of heat is needed to convert 25.0 g of solid ethanol at -135°C to liquid ethanol at -50°C.
The weather in a particular location is influenced by _______. A. Atmospheric movements B. Plant life only C. Population D. Animal migration
Answer: atmospheric movements
Explanation: The weather in a particular location is influenced by atmospheric movements. The movements and interactions of warm and cold air masses. The type of interaction, the speed of the movements, and the area where the interaction occur can impact the type of weather produced.
Imagine that you're doing an experiment that requires you to smell the odor of a chemical solution in a beaker. Which procedure should always be followed? A. Wave the fumes toward your nose with your hand. B. You should never smell chemicals. C. Hold the beaker directly beneath your nose. D. Pour some of the solution on a paper towel and then sniff the towel.
The correct answer really is B.
If you are directed to break that rule then you better be in a high level chemistry class. When I taught things like that I insisted that students just wait until the chemical permeated the fume cabinet and even then I was always very nervous.
Sometimes you have to know when to ignore a bad direction. If you are working with chlorine, for example, you should be especially careful. That stuff was used in WWI as part of a chemical warfare technique. Many men suffered grotesque deaths by breathing it in, particularly if they were in trenches. Chlorine is heavier than air. It sinks to the lowest level.
For the equation N2 + 3H2 → 2NH3 , if you start with 8 moles of nitrogen gas, how many moles of ammonia (NH3) will you have when the reaction is finished?
Answer:
16 mol
Step-by-step explanation:
N₂ + 3H₂ ⟶ 2NH₃
You want to convert moles of N₂ to moles of NH₃.
The molar ratio is 2 mol NH₃:1 mol N₂.
Moles of Br₂ = 8 × 2/1
Moles of Br₂ = 16 mol NH₃
You will have 16 mol NH₃ when the reaction is finished.
In the balancing chemical equations simulation on phet, were you able to use noninteger numbers (like ? or 0.43) for the coefficients in a balanced equation? Why or why not?
Answer: No, we cannot use non-integer numbers for the coefficients in a balanced equation.
Explanation: In a chemical equation, the coefficients are used to determine the number of atoms. As atom is the smallest unit and it cannot be present in fractional form.
So, to write the balanced chemical equations, the coefficients must be natural numbers which starts from 1.
In the balancing chemical equations simulation on PhET or similar tools, you typically cannot use non-integer numbers like decimals or fractions for coefficients in a balanced equation. This limitation exists for several reasons:
Chemical Reality: Chemical reactions involve the rearrangement of atoms and molecules on a discrete scale. Atoms cannot be broken down into fractions or decimals in a chemical reaction. They exist as whole entities, making integer coefficients necessary to represent the actual number of atoms or molecules involved.
Stoichiometry: Balancing equations is critical for stoichiometry, which involves the quantitative relationship between reactants and products. Non-integer coefficients would complicate stoichiometric calculations, making them less accurate and practical.
Chemical Laws: Chemical reactions are governed by fundamental laws, such as the Law of Conservation of Mass, which states that mass is conserved in chemical reactions. Integer coefficients ensure that mass is balanced correctly in the equation.
While non-integer coefficients may be used in certain theoretical contexts, in practical chemical equations and simulations, integer coefficients are used to accurately represent the actual chemical processes and to make stoichiometric calculations feasible and precise.
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What is produced in a double-displacement reaction?
A one new compound
B always a precipitate and a gas
C two pure metallic elements
D two new compounds
The correct answer is option D, that is, two new compounds.
Double displacement also known as double replacement reactions, metathesis or exchange reactions. It take place when two ionic compounds are exchanged forming two new compounds. One can consider the reaction as swapping the anions or the cations.
Water usually functions as the solvent for a double replacement reaction, and the products and reactants are generally ionic compounds, however, they can also be bases or acids. The example of a double replacement reaction is:
BaCl₂ (aq) + Na₂SO₄ (aq) = BaSO₄ (s) + 2NaCl (aq)
In this, the cations are Na⁺ and Ba²⁺, and the anions are SO₄²⁻ and Cl⁻. If the anions or cations are swapped, the products obtained are BaSO₄ and NaCl.
In a double-displacement reaction, two ionic compounds exchange ions in aqueous solution to form two new compounds, often resulting in a precipitate, a gas, or a molecular compound. The correct answer to the given question is option D, two new compounds.
In a double-displacement reaction, two compounds exchange ions to form two new compounds. This typically happens between two ionic compounds in aqueous solution.
The most common outcomes of such reactions are the formation of a solid precipitate, a gas, or a molecular compound like water. The correct answer to what is produced in a double-displacement reaction is D, two new compounds.
An example would be mixing aqueous solutions of potassium iodide (KI) and lead (II) nitrate (Pb(NO₃)₂), resulting in the formation of lead (II) iodide (PbI₂), a precipitate, and potassium nitrate (KNO₃), which remains in solution. This occurs because the lead (II) iodide that is formed is insoluble in water and precipitates out, signifying a successful reaction.
A neutral atom has a mass number of 108 and in atomic number of 47 which atom is this? explain how you know.
^how many Protons electrons and neutrons are in this Atom. Show your calculation or explain how you determine each number
An Adam with an atomic number of 35 makes an ion with a negative 1 charge. Which atom is this? explain how you know.
^ How many electron's does this ion have? Explain how you came to this answer
How many atoms are there in 2 moles of sodium?
A. 6.02 × 10^23 atoms
B. 1.2 × 10^24 atoms
C. 3.32 × 10^24 atoms
D. 2.4 × 10^25 atoms
(NOT A OR D)
B.
One mole of any element or compound contains 6.02x10^23 particles (atoms or molecules)
One mole of a compound has 6.02x10^23 molecules
One mole of an element has 6.02x10^23 atoms
Therefore, 2 moles would have the double of 6.02x10^23 atoms
A mixture with H2 and He exerts a total pressure of 0.48 atm. If there is 1.0 g of H2 and 1.0 g of He in the mixture, what is the partial pressure of the helium gas?
Answer: 0.161 atm
Explanation:
To calculate the partial pressure of helium (He), use the equation PHe = XHe × Ptotal, where XHe is the mole fraction of He, and Ptotal is the total pressure given in the question.
To calculate the mole fraction of helium, we must first calculate the number of moles of helium and hydrogen gas in the mixture.
nHe = 1.00g He/ 4.003 g/mol = 0.2498 mol
nH2 = 1.00g H2 / 2.016 g/mol = 0.4960 mol
ntotal= 0.2498 mol + 0.4960 mol= 0.7458 mol
We can now solve for the partial pressure of helium as follows. Recall that the mole fraction of helium is the ratio of the moles of helium to the total number of moles of gas.
PHe = XHe × Ptotal
= nHe / ntotal × Ptotal
= 90.2498 mol / 0.7458 mol) × 0.480atm
= 0.1608
Therefore, after rounding the answer to two significant figures, we find that the partial pressure of helium gas is about 0.161 atm.
The partial pressure of helium (He) in the mixture containing 1 g of H₂ and 1 g of He is 0.16 atm
We'll begin by calculating the number of mole of each gas present in the mixture.
For H₂:Mass of H₂ = 1 g
Molar mass of H₂ = 2 × 1 = 2 g/mol
Mole of H₂ =?Mole = mass / molar mass
Mole of H₂ = 1/2
Mole of H₂ = 0.5 moleFor He:Mass of He = 1 g
Molar mass of He = 4 g/mol
Mole of He =?Mole = mass / molar mass
Mole of He = 1/4
Mole of He = 0.25 moleNext, we shall determine the total mole.
Mole of H₂ = 0.5 mole
Mole of He = 0.25 mole
Total mole =?Total mole = 0.5 + 0.25
Total mole = 0.75 moleNext, we shall determine the mole fraction of He.
Mole of He = 0.25 mole
Total mole = 0.75 mole
Mole fraction of He =.?
Mole fraction = mole / total mole
Mole fraction of He = 0.25 / 0.75
Mole fraction of He = 0.33Finally, we shall determine the partial pressure of He.
Mole fraction of He = 0.33
Total pressure = 0.48 atm
Partial pressure of He =?Partial pressure = mole fraction × total pressure
Partial pressure of He = 0.33 × 0.48
Partial pressure of He = 0.16 atm
Therefore, the partial pressure of helium (He) in the mixture is 0.16 atm
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CHEM HELP?!? Carbon tetrachloride has been widely used in the cleaning industry, in fire extinguishers, and as a refrigerant. Construct an explanation of how carbon and chlorine combine to form carbon tetrachloride.
A) Nonmetal carbon shares valence electrons with each nonmetal chlorine forming four covalent bonds.
B) Nonmetal carbon loses a valence electron and chlorine metal gains a valence electron to form an ionic bond.
C) Carbon and chlorine are nonmetals and they shares their valence electrons to become ions and form ionic bonds.
D) Chlorine metal loses a valence electron to become a cation and nonmetal carbon gains a valence electron to become an anion forming a covalent bond.
Answer: A) Nonmetal carbon shares valence electrons with each nonmetal chlorine forming four covalent bonds.
Explanation: Carbon has atomic no 6. It has 4 valence electrons. It can only share electrons as it is difficult to gain or lose 4 electrons to complete it's octet.
Chlorine has atomic no 17 . It has 7 valence electrons and need one electron to complete its octet.
Thus carbon will share 4 electrons, one each with four chlorine atoms to form carbon tetra chloride.
Covalent bond is formed by sharing of electrons whereas Ionic bond is formed by transfer of electrons between atoms.
Answer:
its A
Explanation:
did it on usa test prep
How many moles of chlorine are in 100g chlorine (Cl)?
A) 0.355
B) 100
C) 64.6
D) 2.82
Answer: D) 2.82
Reasoning: There are 35.453 grams in a single mole.
So divide 100 by 35.453
100/35.453=2.82063577
Rounded 2.82063577 equals 2.82
There are 2.82 moles of chlorine in the 100 gram of chlorine. A mole is a unit of measurement that is used for very tiny particles such as atoms, ions, and molecules.
What is Mole Concept?A mole is a unit of measurement that is used for very tiny particles such as atoms, ions, and molecules. 1 mole is equal to the Avogadro's constant that is [tex]6.2\times 10^{23}[/tex].The number of moles can be calculated by the formula,
[tex]n = \dfrac wm[/tex]
Where,
[tex]n[/tex]- number of moles
[tex]w[/tex] - given mass of chlorine
[tex]m[/tex] - molar mass of the chlorine
Put the values in the formula,
[tex]n = \dfrac {100}{35.45}\\\\n = 2.82 \rm \ g[/tex]
Therefore, there are 2.82 moles of chlorine in the 100 gram of chlorine.
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Which of the following provides evidence to support Rutherford's model of the atomic nucleus?
A. Gold foil experiment
B. Plum pudding model
C. Spectrum of colors emitted by gas
D. Radiation produced when alpha particles hit beryllium
the answer is A: The Gold Foil experiment
Answer: A. Gold foil experiment
Explanation:
Ernest Rutherford discovered the nucleus in 1911 from the results he obtained in several experiments in which he bombarded a thin sheet of gold with alpha particles (a sub-microscopic particle with a positive charge) from a radioactive element.
Rutherford observed, by means of a fluorescent screen, to what extent the particles with which he bombarded the sheet were scattered. Most of them traversed the metal sheet without changing direction; however, a few were reflected backwards with small angles.
Using a mathematical analysis of the forces involved, Rutherford showed that the scattering was caused by a small positively charged nucleus, located in the center of the gold atom. In this way, he deduced that most of the atom is empty space and discovered the atomic nucleus.
Be sure to answer all parts. Dinitrogen difluoride, N2F2, is the only stable, simple inorganic molecule with an N=N bond. The compound occurs in cis and trans forms. (a) Select which of the molecular shapes of N2F2 correspond to the cis and trans form of N2F2. I h5a II h5b III h5c cis-dinitrogen fluoride: I II III trans-dinitrogen fluoride: I II III (b) Predict the polarity, if any, of each form. cis = polar; trans = polar cis = polar; trans = nonpolar cis = nonpolar; trans = polar cis = nonpolar; trans = nonpolar
(a) The molecular shapes of cis and Trans forms of N2F2 are-
b) There is EN difference between N atom and F atom. Hence the molecule will have a bond dipole.
In Cis form two fluorine atoms are on the same side of N N bond. Hence, bond moment in N2F2 cis form) do not cancel each other. Thus the cis form is polar.
In the trans form two fluorine atoms are on the opposite side of N-N bond. Bond moment of NF cancels each other.
Thus: trans N2F2 is non polar molecule.
Answer:
(a) The molecular shapes of cis and Trans forms of N2F2 are-
b) There is EN difference between N atom and F atom. Hence the molecule will have a bond dipole.
In Cis form two fluorine atoms are on the same side of N N bond. Hence, bond moment in N2F2 cis form) do not cancel each other. Thus the cis form is polar.
In the trans form two fluorine atoms are on the opposite side of N-N bond. Bond moment of NF cancels each other.
Thus: trans N2F2 is non polar molecule.
HELP!
What is a property of an ionic compound?
Select all that apply.
conducts electricity and heat efficiently
insulates against heat and electricity
resists melting at high temperatures
remains intact when soaked in water
Answer: conducts electricity and heat efficiently, resists melting at high temperatures.
Explanation: Ionic compounds are formed by transference of electrons and leads to generation of cations and anions which are held by strong coloumbic forces. eg: NaCl
Ionic compounds when dissolved in water dissociates into ions and thus are good conductors of heat and electricity.
They are conductors not insulators.
They have very high melting points as they are held by strong coloumbic forces.
They dissociate into ions when dissolved in water.
[tex]NaCl\rightarrow Na^++Cl^-[/tex]
Ionic compounds conduct electricity and heat efficiently, resist melting at high temperatures and can remain intact when soaked in water because of their ionic bonds formed due to the exchange of electrons between a metal and a nonmetal.
The properties of an ionic compound include their tendency to conduct electricity and heat efficiently, to resist melting at high temperatures, and to remain intact when soaked in water. Ionic compounds are formed when a metal and nonmetal exchange electrons, creating ions that are attracted to each other due to their opposite charges. Since their positively and negatively charged ions can move freely when they're dissolved or melted, they can conduct heat and electricity efficiently.
The strong ionic bonds in an ionic compound make them resist melting at high temperatures. Lastly, ionic compounds will remain intact but not dissolve in nonpolar solvents like oil, but they will dissolve in polar solvents like water, hence they can remain intact when soaked in water.
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The silver isotope with 60 neutrons. Enter the chemical symbol of the isotope.
Ag with a superscript of 107 and a subscript of 47
The silver (Ag) isotope with 60 neutrons has the chemical symbol: [tex] ^{107}_{47}X [/tex].
Any isotope can be represented as follows:
[tex] ^{A}_{Z}X [/tex]
Where:
Z: is the atomic number = number of protons
A: is the mass number
The atomic number of Silver is 47, so:
[tex] ^{A}_{47}X [/tex]
Now, we need to find the mass number:
[tex] A = Z + n [/tex]
Where:
n: is the number of neutrons = 60
[tex] A = Z + n = 47 + 60 = 107 [/tex]
Therefore, the chemical symbol of Ag-47 is [tex] ^{107}_{47}X [/tex].
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Which of the following best describes how further studies supported Joseph Proust's discovery about proportion of elements in water?
Max Planck discovered the Planck's constant.
John Dalton proposed that matter is made of tiny particles.
James Chadwick discovered neutral particles in the nucleus of the atom.
Niels Bohr determined that electrons inhabit distinct energy levels.
Answer is: John Dalton proposed that matter is made of tiny particles.
Proust's law or law of constant composition said that a given chemical compound always contains its component elements in fixed ratio and does not depend on method of preparation.
Water (H₂O) is made of two hydrogen atoms and one oxygen atom:
m(H) : m(O) = 2·1 : 16 = 1: 8.
Dalton said that matter is composed of atoms and atoms of different elements can join to form chemical compound.
How much fluorine (in grams) does the second sample produce?
I divided 2.58kg of fluorine by the 1.24kg of magnesium, but I'm not sure that's the right way to do this. Should I cross multiply? I read the page in the book, and it had nothing to do with a problem like this.
Answer: 1.94 kg
Explanation: Given : [tex]MgF_2\rightarrow Mg+F_2[/tex]
Sample 1 produces 1.65 kg of Mg and 2.58 kg of [tex]F_2[/tex].
As every chemical reaction follows law of conservation of mass, which says that the mass of products must be equal to the mass of reactants.
Thus mass of [tex]MgF_2[/tex] should be 1.65+2.58 kg = 4.23 kg
1.65 kg of Mg was produced by 4.23 kg of [tex]MgF_2[/tex]
Now the second sample produces 1.24 kg of Mg.
1.24 kg of Mg will be produced by=[tex]\frac{4.23}{1.65}\times {1.24}=3.18 kg[/tex]
Now again law of conservation of mass is to be followed so mass of [tex]F_2[/tex] will be= mass of [tex]MgF_2[/tex] - mass of [tex]Mg[/tex]
=(3.18 kg -1.24 kg) = 1.94 kg
What type of organic compound has the empirical formula CH2O and can serve as energy storage or the starting material for fats and amino acids?
Amine
Carbohydrate
Carbonyl
Ketone
*please explain your answer for brainliest
Answer:
Carbohydrates
Explanation:
Did the test and got it right
A container holds 500. ML of CO2 at 20.° C and 742 torr. What will be the volume of the CO2 if the pressure is increased to 795 torr?
Answer: 466.67 ml
Explanation:
Boyle's Law: This law states that pressure is inversely proportional to the volume of the gas at constant temperature and number of moles.
[tex]P\propto \frac{1}{V}[/tex] (At constant temperature and number of moles)
Thus
[tex]P_1V_1=P_2V_2[/tex] [according to Boyle's law]
[tex]742torr\times 500ml=795torr\times V_2[/tex]
[tex]V_2=466.67ml[/tex]
Answer : The volume of [tex]CO_2[/tex] will be 0.4665 L
Solution : Given,
Initial volume = 500 ml = 0.5 L (1 L = 1000 ml)
Initial pressure = 742 torr = [tex]\frac{742}{760}=0.976atm[/tex] [tex](1atm=760torr)[/tex]
Final pressure = 795 torr = [tex]\frac{795}{760}=1.046atm[/tex]
According to the Boyle's law, the pressure of the gas is inversely proportional to the volume of the gas at constant temperature.
[tex]P\propto \frac{1}{V}[/tex]
or, [tex]\frac{P_1}{P_2}=\frac{V_2}{V_1}[/tex]
where,
[tex]P_1[/tex] = initial pressure of the gas
[tex]P_2[/tex] = final pressure of the gas
[tex]V_1[/tex] = initial volume of the gas
[tex]V_2[/tex] = final volume of the gas
Now put all the given values in the above formula, we get
[tex]\frac{P_1}{P_2}=\frac{V_2}{V_1}[/tex]
[tex]\frac{0.976atm}{1.046atm}=\frac{V_2}{0.5L}[/tex]
By rearranging the terms, we get the final volume of the gas.
[tex]V_2=0.4665L[/tex]
Therefore, the volume of [tex]CO_2[/tex] will be 0.4665 L
Match the prefix with the power of ten it represents.
1. mega 10-2
2. kilo 103
3. hecto 10-3
4. deka 106
5. deci 10-1
6. centi 101
7. milli 10-6
8. micro 102
Answer:
Mega- 10^6
Kilo-10^3
Hecto- 10^2
Deca-10^1
Deci-10^-1
Centi-10^-2
Milli-10^-3
Micro-10^-6
All are metric system units
The correct matching of prefixes with the powers of ten they represent is as follows:
1. mega - [tex]\(10^6\)[/tex]
2. kilo - [tex]\(10^3\)[/tex]
3. hecto - [tex]\(10^2\)[/tex]
4. deka - [tex]\(10^1\)[/tex]
5. deci - [tex]\(10^{-1}\)[/tex]
6. centi - [tex]\(10^{-2}\)[/tex]
7. milli - [tex]\(10^{-3}\)[/tex]
8. micro -[tex]\(10^{-6}\)[/tex]
The metric system uses prefixes to denote powers of ten. Here is the explanation for each prefix:
1. Mega (M) is a prefix that stands for one million times the base unit, hence [tex]\(10^6\).[/tex]
2. Kilo (k) is a prefix that stands for one thousand times the base unit, hence [tex]\(10^3\).[/tex]
3. Hecto (h) is a prefix that stands for one hundred times the base unit, hence [tex]\(10^2\).[/tex]
4. Deka (da) is a prefix that stands for ten times the base unit, hence \[tex](10^1\).[/tex]
5. Deci (d) is a prefix that stands for one-tenth of the base unit, hence \[tex](10^{-1}\).[/tex]
6. Centi (c) is a prefix that stands for one-hundredth of the base unit, hence [tex]\(10^{-2}\).[/tex]
7. Milli (m) is a prefix that stands for one-thousandth of the base unit, hence [tex]\(10^{-3}\).[/tex]
8. Micro (µ) is a prefix that stands for one-millionth of the base unit, hence [tex]\(10^{-6}\).[/tex]
The powers of ten are used to express very large or very small numbers concisely. Each prefix represents a specific multiple or fraction of the base unit. For example, a millimeter (mm) is one-thousandth of a meter, and a kilogram (kg) is one thousand times the mass of a gram.
what number of electrons balances the charges in this half reaction
[tex]so2 +2h2o so {4}^{2 -} + 4h + [/tex]
Answer : Two electrons balances the charges in this half reaction.
Explanation :
The given half reaction is,
[tex]SO_2+2H_2O\rightarrow SO^{2-}_4+4H^+[/tex]
In this half reaction, there is no charges present on the left side of the reaction but on right side of the reaction, (2+) charge is present. So, two electrons (2-) are added on the right side of the reaction for balances the charge of the half reaction.
The balanced half reaction is,
[tex]SO_2+2H_2O\rightarrow SO^{2-}_4+4H^++2e^-[/tex]
Hence, two electrons balances the charges in this half reaction.
PLEASE HELP What is the mass of sodium in 50 grams of salt? Show your work.
50 grams salt
Volume of 50 Grams of Salt
50 Grams of Salt =
2.78 Tablespoons
8.33 Teaspoons
0.17 U.S. Cups
0.14 Imperial Cups
Answer:
19,7g of Na
Explanation:
The molecular formula of common salt is NaCl, the molar mass is molar mass of Na + molar mass of Cl:
22,99g/mol + 35,45 g/mol = 58,44 g/mol
Thus, 50g of NaCl contains:
50g × (1mol / 58,44g) = 0,856 moles.
If 1 mole of Na are 22,99g, 0,856 moles are:
0,856 moles × (22,99g / 1mol) = 19,7g of Na
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Acetylcholine binds to its receptor in the sarcolemma and triggers __________.
a. the opening of voltage-gated calcium channels
b. the opening of ligand-gated cation channels
c. the opening of calcium-release channels
d. the opening of ligand-gated anion channels
Acetylcholine binds to its receptor in the sarcolemma and triggers B. The opening of ligand-gated cation channels.
Acetylcholine refers to an organic chemical that functions in the brain. It's typically a chemical message that's released by the nerve cells in order to send signals to the other cells like the muscles cells, neurons, etc.
When acetylcholine binds to its receptor in the sarcolemma, this lead to the triggering of the opening of ligand-gated cation channels. These is vital for controlling synaptic transmission between the neurons.
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For diffusion to occur, which condition must be met?
A) A concentration gradient must exist.
B) A hypotonic external environment is required.
C) A hypertonic external environment is required.
D) Dynamic equilibrium must exist.
Answer:
A) A concentration gradient must exist.
Explanation:
For diffusion to occur there must be a concentration gradient. Diffusion occurs when particles move from a region of high concentration to a region of lower concentration. Diffusion occurs until there is equal concentration on both sides. Diffusion stops when concentration equilibrium is reached.
For diffusion to occur, the condition that must be met is: A) A concentration gradient must exist.
What condition must be met for diffusion?Diffusion requires a concentration gradient to occur. In other words, there must be a difference in the concentration of a substance between two regions. When there is a higher concentration of a substance in one area compared to another, the particles of that substance will naturally move from the region of higher concentration to the region of lower concentration.
This movement continues until equilibrium is reached where the concentration becomes equalized. Therefore, the presence of a concentration gradient is a crucial condition for diffusion to take place. Therefore, the Option A is correct.
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Name the element that has a full s and p orbital in the second period.
Answer: Neon
Explanation: The second period involves elements with n =2 i.e. the elements have electrons in second shell. The element with filled s and p orbitals will have outer electronic configuration [tex]2s^22p^6[/tex]
Thus the element with filled orbital will be a noble gas. It will have total of 10 electrons and the element will be neon with complete outer electronic configuration will be:
[tex]1s^22s^22p^6[/tex]
When a reaction occurs between atoms with ground state electron configuration 1s2 2s1 and 1s2 2s2 2p5 the predominant type of bond formed is
Answer:
Ionic
Explanation:
Step 1: Define
1s²2s¹ is Lithium (Li)
1s²2s²2p⁵ is Chlorine (Cl)
Step 2: RxN
2Li (s) + Cl₂ (g) → 2LiCl (s)
Step 3: Identify
LiCl is a metal and a non-metal bonded together. Therefore, it will be an ionic bond. The Lithium would transfer it's electron to Chlorine (since it wants a full outer shell 0f 8 and it currently as 7) and form a salt.
What do the lines around the finger of the doorknob represent?
The lines around the finger of the doorknob represent the electric force on the charged objects.
unlike the jungles you see in movies, the floor of an i disturbed tropical rain forest usually has little vegetation. explain why it lacks vegetation
Because in The jungle almost no sunlight hits the floor so plants are able to live.
The dense canopy layer of the tropical rainforest obstructs sunlight from reaching the forest floor, making it difficult for plants to grow. Despite the lack of light, the forest maintains high net productivity due to ideal weather conditions.
Explanation:The primary reason why the floor of an undisturbed tropical rainforest lacks vegetation is due to the dense canopy layer of the rainforest. The constant interlocking of broad leaves and branches in the upper parts of the trees, known as the canopy, blocks most of the sunlight from reaching the forest floor.
Nevertheless, the rainforest still maintains a high net primary productivity due to the ideal annual temperatures and precipitation values that are perfect for plant growth. However, due to the shaded conditions, only a sparse layer of plants and decaying plant matter can typically survive on the forest floor.
The tall trees that form this dense canopy have adapted to grow in close proximity to each other so as to efficiently use the available light in the canopy. This makes the floor of a rainforest much darker and less hospitable to the growth of a large number of plant species compared to the typical lush, green jungle often depicted in movies.
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Identify the formula for the binary covalent compound,
phosphorus pentabromide.
A.
PBr5
B.
PBr5
C.
5PBr
D.
P5Br
Answer:
A. PBr5
Explanation:
To write the formulas for a compound, first identify what the elements used are.
In phosphorus pentabromide, the elements are phosphorus and bromine (bromine => bromide in a compound name). Find these symbols on your periodic table.
Phosphorus = P
Bromine = Br
Write them one after the other:
PBr
Then, determine the number of each atom, which will be written as a subscript. The word penta is the greek prefix meaning 5. Since it's attached to "bromide", there are 5 bromine atoms.
PBr₅
The formula for the binary covalent compound phosphorus pentabromide is PBr5. This is due to the 'penta' prefix indicating five atoms of bromine and one atom of phosphorus.
Explanation:The correct formula for the binary covalent compound phosphorus pentabromide is PBr5. The prefix 'penta' indicates five, so pentabromide implies there are 5 bromine (Br) atoms. Phosphorus (P), in this case, does not have a prefix, which means there is one phosphorus atom. Therefore, combining one atom of phosphorus with five atoms of bromine gives us PBr5.
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Ce procent de impuritati contine un minereu de siderit, daca din 1500kg minereu s-au obtinut 700kg fier 90% ?
FeCO3 ==> Fe + produsi minoritari.
m Fe impur= 700 kg
puritatea (p) = masa pura (mp)/ masa impura (mi) x 100
mp= p x mi / 100 sau mp = p/100 x mi => mp Fe = 90/100 x 700 = 630 kg Fe pur.
M FeCO3= 115.85 kg/kmol
115.85 kg FeCO3 .... 55.85 kg Fe
x kg FeCO3 ........630 kg Fe
x= 630 * 115.85 /55.85 = 1306.81 kg FeCO3 (mp in formula puritatii)
p=mp/mi x 100
mi FeCO3 = 1500 kg
mp FeCO3=1306.81 kg
p=1306.81 / 1500 x 100 = 87.12% puritate Siderit
Answer:
It has 12.84% of impurity
Explanation:
You obtained 700 kg 90% purity of Fe, so you have:
[tex]m_{Fe}=700 kg*0.9=630kg[/tex]
Those 630 kg are the mass of Fe contained in the original sample of 1500 kg in the from of Siderit.
The other substeances that aren't Siderit in the sample can be considered impurities.
Siderit: [tex]FeCO_3[/tex]
[tex]M_{siderit}=115.8 kg/kmol[/tex]
[tex]M_{Fe}=55.8 kg/kmol[/tex]
The mass of siderit:
[tex]m=630 kg Fe*\frac{115.8 kg Siderit}{55.8 kg Fe}=1307.4 kg Siderit[/tex]
[tex]m_{impurities}=1500kg-1307.4kg=192.6kg[/tex]
Percentaje of impurity:
[tex]P=\frac{192.6kg}{1500kg}*100=12.84[/tex]
Who is the chemist who is given credit for developing the modern periodic table?
No answer provided
a. Mendeleev
b. Newlands
c. Dobereiner
d. Moseley
Answer:
Mendeleev
Explanation: