the mass of ice taken = 10 g
the mass of water = 250 g
initial temperature of water = 20 C
the final temperature of water = 16. 8 C
specific heat of water = 4.18 J/g*K
the heat absorbed by ice to melt = heat loss by water
heat loss by water = mass X specific heat of water X change in temperature
heat loss by water = 250 X 4.18 X (20-16.8) = 3344 Joules
heat gained by ice = 3344 J
heat gained by ice = enthalpy of fusion X moles of ice
moles of ice = mass / molar mass = 10 / 18 = 0.56 moles
enthalpy of fusion = 3344 / 0.56 = 5971.43 J / mole
Which of the following shows a physical change?
A. H2(g)+O2(g)=H2O(l)
B. 2CH3OH(l)+3O2(g)=2CO2(g)+4H2O(l)
C. NaCl(s)=NaCl(aq)
D. 2AgNO3(aq)+CaBr2(aq)=2AgBr(s)+Ca(NO3)2(aq(
NaCl(s)=NaCl(aq) is a physical change as it represents a state change from solid to aqueous but retains the same chemical nature, Sodium Chloride (NaCl). The other choices show chemical changes.
The correct option is c.
Explanation:The question is asking which of the choices represents a physical change. A physical change involves changes in the state of a substance but not its chemical nature. The best answer here is option C: NaCl(s)=NaCl(aq). In this reaction, solid sodium chloride (NaCl) is dissolving in water to form an aqueous solution, which is just a change in the state from solid to aqueous but the chemical nature (NaCl) remains the same. This is a clear demonstration of a physical change whereas options A, B, and D show chemical changes where new substances are formed.
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C. [tex]NaCl(s) \rightarrow NaCl(aq)[/tex] shows a physical change.
A physical change is a type of change in which the form of matter is altered, but one substance is not transformed into another. Examples of physical changes include changes in state such as melting, freezing, and dissolving.
A. [tex]H_2(g) + O_2(g) \rightarrow H_2O(l)[/tex]
This is a chemical change because new substances with different chemical properties are formed: hydrogen and oxygen combine to form water.
B. [tex]2CH_3OH(l) + 3O_2(g) \rightarrow 2CO_2(g) + 4H_2O(l)[/tex]
This is another chemical change, involving the combustion of methanol to form carbon dioxide and water.
C. [tex]NaCl(s) \rightarrow NaCl(aq)[/tex]
This is a physical change. When sodium chloride (table salt) dissolves in water, it dissociates into ions but does not undergo any chemical change.
D. [tex]2AgNO_3(aq) + CaBr_2(aq) \rightarrow 2AgBr(s) + Ca(NO_3)_2(aq)[/tex]
This is a chemical change, where silver nitrate and calcium bromide react to form silver bromide and calcium nitrate, both of which are new substances.
what is the tripple point on a phase diagram?
Final answer:
The triple point on a phase diagram represents the only combination of temperature and pressure at which all three phases can exist simultaneously and are in equilibrium.
Explanation:
The triple point on a phase diagram refers to the point where the solid/liquid, liquid/gas, and solid/gas lines intersect. It represents the only combination of temperature and pressure at which all three phases can exist simultaneously and are in equilibrium. An example is the triple point of water, which occurs at 273.16 K (0.01°C). At this point, water can exist simultaneously as solid ice, liquid water, and water vapor.
which process responsiblr for the growth a repair pf human tissue?
Hey there!
"Which process responsible for the growth a repair of human tissue?"
[tex]1. evolution[/tex][tex]2. germination[/tex][tex]3. cell[/tex][tex]division[/tex][tex]4. natural[/tex] [tex]selection[/tex]Well, it heals itself which is called the mitosis but none of those are your answer choices .. the one that seems to be closer to those two results would be: Option 3. [tex]\boxed{cell-division}[/tex]
Therefore, your answer would most likely be: [tex]\boxed{cell-division}[/tex]
Good luck on your assignment and enjoy your day!
~[tex]LoveYourselfFirst:)[/tex]
Most pure liquids and gases we encounter on a daily basis are covalently-bonded instead of being ionically bonded. This must mean that covalently-bonded substances usually ________ than ionically-bonded substances. A. are less organized B. are more organized C. form stronger bonds D. share less electrons
D - are more organized
Answer: Are less organized
Explanation:
The formation of a solid has to do with a very ordered arrangement of molecules in a regular repeating pattern. The arrangement of molecules must be neat enough to allow close packing of the ordered arrangement. Ionically bonded species have a neat arrangement of oppositely charged ion pairs. This accounts for their abundant existence in the solid state. There is less order in the packing of covalent molecules as they as mostly held by weak intermolecular forces. Hence they exist mostly as liquids and gases.
How many atoms of Iodine are in a 12.75g sample of CaI2?
Answer: [tex]5.2\times 10^{22} atoms[/tex] of iodine are present in 12.75 grams of [tex]CaI_2[/tex].
Explanation:
[tex]moles=\frac{\text{given mass of the compound}}{\text{molar mass of the compound}}[/tex]
Moles of Calcium iodide :
Moles of [tex]CaI_2=\frac{12.75 g}{293.8 g/mol}=0.0433 moles[/tex]
number of molecules of [tex]CaI_2[/tex] in 0.0433 moles = [tex]N_A\times \text{number of moles}=6.022\times 10^{23}\times 0.0433=2.60\times 10^{22} molecules [/tex]
In one molecule of calcium iodide there are two iodine atoms, then number of iodine atoms in [tex]2.60\times 10^{22} molecules [/tex] of [tex]CaI_2[/tex]
[tex]2\times 2.60\times 10^{22} atoms=5.2\times 10^{22} atoms[/tex]
Hence, there are [tex]5.2\times 10^{22} atoms[/tex] of iodine are present in 12.75 grams of [tex]CaI_2[/tex].
A chemical that causes a sudden almost instantaneous release of pressure has and heat when subjected to sudden shock pressure or high temperatures best describes which type of DOT hazardous materials classification
A hazardous chemical instantly discharging gas, pressure, and heat when subjected to pressure, heat, or high temperature is categorized under hazard class I explosives by the Department of Transportation.
These are the explosives that possess the tendency to briskly detonate or conflagrate as an outcome of the chemical reaction. The explosives possess the tendency of generating pressures, temperatures, and speeds as leading to catastrophic destruction via force and/or of generating otherwise hazardous concentrations of light, heat, gas, sound, or smoke, all this resulting due to chemical reactions.
the electrostatic attraction between positively charged nuclei and negatively charged electrons permits two atoms to be held together by a[n]
The electrostatic attraction between positively charged nuclei and negatively charged electrons permits two atoms to be held through either a covalent bond, where the electrons are shared between atoms, or an ionic bond, where one atom donates or accepts an electron from the other, creating ions which are attracted to each other.
Explanation:The electrostatic attraction between positively charged nuclei and negatively charged electrons allows two atoms to be held together through what is known as a covalent bond or an ionic bond. In a covalent bond, these forces of attraction are between the nuclei of a molecule's atoms and pairs of electrons between these atoms. For instance, in an oxygen molecule O₂, the electrons are equally shared between the atoms, establishing a covalent bond.
On the other hand, in an ionic bond, a atom donates or accepts an electron resulting in a positively or negatively charged atom, termed as an ion. For example, a sodium (Na) atom can donate its 2s electron to a chlorine (Cl) atom. This results in a positively charged Na+ ion and a negatively charged Cl- ion. The electrostatic attraction between these charged ions creates an ionic bond and forms a salt molecule (NaCl).
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in a chemical reaction, ... interact to form ...
a. molecules, atoms
b. products, reactants
c. elements, atoms
d. reactants, products
The answer is letter D. Reactants, Products
In ____________, electrons are gained by atoms and lost by others.
A) ionic bonds
B) covalent bonds
C) metallic bonds
D) polyatomic bonds
Answer: The correct answer is Option A.
Explanation:
From the given options:
A. Ionic bonds: These bonds are formed when there is complete transfer of electrons from one atom to another atom. An atom which looses electrons is known as electropositive atom and the atoms which gains electrons is known as electronegative atom.
B. Covalent Bonds: These bonds are formed when there is sharing of electrons between the two atoms.
C. Metallic bonds: These bonds are formed from the attraction between the free electrons and fixed positively charged of two metallic atoms.
D. Polyatomic Bonds: These bonds are formed between the species forming a polyatomic ion.
From the given information, the correct answer to this question is Option A.
Answer:
The correct answer here is ionic bond
Explanation:
A food item that is left out of the refrigerator turns brown and forms bubbles and gas. What are the signs that this is a chemical reaction? Check all that apply. * 2 points Heat is produced Bubbles appear. The color changes. Heat is absorbed. A precipitate forms.
The formation of bubbles and the change in color of the food item are signs of a chemical reaction, indicating the production of gas and the creation of new substances.
When a food item left out of the refrigerator turns brown, forms bubbles, and releases gas, the signs that a chemical reaction has occurred include the production of gas (evidenced by bubbles) and a change in color. These are key indicators that the original substances have undergone a chemical change to form new substances with different properties. While heat can be absorbed or produced during a chemical reaction, the question does not specify that this occurred, and there is no mention of a precipitate being formed.
Macho Mel can lift 200 kilograms with case. How much is this in pounds?
he can lift 440.925 pounds
Macho Mel can lift approximately 440.924 pounds, as 200 kilograms is equal to 440.924 pounds when using the conversion factor of 1 kilogram being approximately 2.20462 pounds.
To convert kilograms to pounds, one must use the conversion factor where 1 kilogram equals approximately 2.20462 pounds. So, by multiplying 200 kilograms by this conversion factor, we find that Macho Mel can lift:
200 kg x 2.20462 lbs/kg = 440.924 lbs
Therefore, Macho Mel can lift 440.924 pounds with ease.
Which two particles can form an ionic bond with each other?
A.
a negative oxygen ion and a negative chlorine ion
B.
a positive sodium ion and a positive magnesium ion
C.
a positive calcium ion and a negative oxygen ion
D.
a neutral fluorine atom and a negative sulfur ion
The correct answer is C. A positive calcium ion and a negative oxygen ion
Explanation:
In chemistry, an ionic bond occurs as ions with opposite charges attract each other and then create a bond due to the transference of electrons from one atom to other. This means, this type of bond occurs between an atom that is positively charged and one that is negatively charged, therefore, the two particles that can form an ionic bond are "A positive calcium ion and a negative oxygen ion" because these two have opposite charges (one is positively charged and one is negatively charged) and therefore electrons can be transferred from one atom to another forming an ionic bond.
how much iron can be recovered from 25 grams of Fe2O3
Answer: The mass of iron recovered is 17.5 grams
Explanation:
We are given a chemical compound having chemical formula of [tex]Fe_2O_3[/tex]
We know that:
Molar mass of iron (III) oxide = 159.7 g/mol
Mass of iron = 55.8 g/mol
We are given:
Mass of iron (III) oxide = 25 g
To calculate the mass of iron recovered in given amount of iron (III) oxide, we use unitary method:
From 159.7 grams of iron (III) oxide, mass of iron recovered is [tex](2\times 55.8)g[/tex]
So, from 25 grams of iron (III) oxide, mass of iron recovered will be [tex]\frac{(2\times 55.8)}{159.7}\times 25=17.5g[/tex]
Hence, the mass of iron recovered is 17.5 grams
The iron that will be recovered from 25 g of [tex]\bold{Fe_2O_3}[/tex] is
What is ferric oxide?Ferric oxide is an organic compound with the chemical formula [tex]\bold{Fe_2O_3}[/tex]. It is one of the three main oxides of iron.
Given,
Mass of [tex]\bold{Fe_2O_3}[/tex] is 25 gram
Molar mass of iron oxide is 159.7
Mass of iron is 55.8 g
To calculate the amount of iron
From 159.7 g of ferric oxide, the amount of iron we found is [tex]55.8\;g \times 2[/tex]
So, from 25 grams of ferric oxide, the mass of iron recovered will be
[tex]\dfrac{55.8 \times 2}{159.7} \times25 = 17.5 g[/tex]
Thus, the mass of iron recovered is 17.5 g.
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Which of the following can be expected to occur as climate changes continues on Earth?
A] decreased melting of sea ice
B] decreased migration of pets and pathogens
C] increased freshwater sources
D] increased coastal flooding
The correct answer is option D, that is, increased coastal flooding.
The change in climate is enhancing the frequency of coastal flooding, comprising floods just from tides. The combination of melting of ice into the oceans and expansion of water as the ocean has warmed has increased the level of the sea up to about seven inches since 1900, and the elevation is on the rise.
From 2005 to 2015, the average number of floods has doubled along the stretch of coast from Florida to North Carolina. The flooding will become even more usual in the coming time as the concentration of greenhouse gases discharged into the atmosphere will increase the levels of the sea in years to come.
Which of the following has can make 3 bonds ?
A-sodium (Na)
B-Neon (Ne)
C-Oxygen(O)
D-Nitrogen(N)
The answer is D-Nitrogen(N).
Nitrogen has three unpaired valence electrons, therefore, it can form three covalent bonds.
During the formation of a tornado,
cool air condenses
warm air evaporates
cool and warm air sink
cool and warm air meet
The very last option is the correct answer.
Answer: Option (4)
Explanation: For the formation of a tornado, warm air must meet the cold air.
Initially, the warm air present in the lower atmosphere, gets heated up, being less dense, rises up and mixes up with the cold and denser air mass present in the upper atmosphere. Due to this collision of both the air masses, and the presence of water vapor, it gets converted into water droplets and formation of clouds. With time a more intense funnel forms due to the wind from all direction and forms a tornado.
Thus, the correct answer is option (4).
A mixture of three noble gases has a total pressure of 1.25 atm. The individual pressures exerted by neon and argon are 0.68 atm and 0.35 atm, respectively. Wha t is the partial pressure of the third gas, helium?
This problem can be solved by Dalton's law of partial pressures which states that in a mixture of non-reacting gases, the total pressure exerted is equal to the sum of the partial pressures of the individual gases.
Ptotal = P₁ + P₂ + P₃ + ..... + Pn
Herein, Ptotal = P(Ne) + P(Ar) + P(He)
Ptotal = 1.25 atm, P(Ne) = 0.68 atm and P(Ar) = 0.35
So, P(He) = Ptotal - P(Ne) - P(Ar) = 1.25 - 0.68 - 0.35 = 0.22 atm
Answer:
0.22 atm
Explanation:
took test
When you heat a sample of a solid, the particles that make up the solid: * 0/1
get bigger
lose mass
move faster
slow down
Final answer:
The correct answer is "move faster". When a solid is heated, the particles that compose it move faster due to an increase in their average kinetic energy. The solid may expand overall, but the individual particles do not get bigger, lose mass, or slow down. The temperature rise is an indication of the increased vibrational motion of the particles within the solid.
Explanation:
When you heat a sample of a solid, the particles that make up the solid move faster. This happens because heating a substance increases the amount of thermal energy, which then increases the average kinetic energy (KE) of the particles. At a microscopic level, a solid consists of molecules and atoms vibrating quickly in place when hot, and moving slowly when cold, without any chemical reaction or phase change like melting or vaporizing. In a solid, these particles are in a constant state of vibration, and as they are heated, they gain energy and vibrate more quickly, which we interpret as an increase in temperature.
As the temperature rises, it's an excellent approximation that solids expand in each dimension by a specific fraction, assuming no constraints on their expansion. However, the particles themselves do not get bigger, lose mass, or slow down when heated. Instead, the increase in temperature may cause the solid to expand overall, while the proportions of the solid remain constant. This is because the interaction potential curve between particles is usually asymmetric, becoming less steep at greater distances and showing an increase in equilibrium particle-particle distance when the substance is heated.
If we consider endothermic processes like melting, the added heat increases the speed of the molecules causing them to move faster. In contrast, exothermic processes like freezing decrease the speed of the molecules causing them to move slower. Hence, the correct answer is that the particles move faster when a solid is heated.
• N2 • CCl4 • SiO2 • AlCl3 why are they covalent
How does a catalyst speed up a chemical reaction
Answer: by lowering the activation energy.
Explanation:
Activation energy is the extra energy that must be supplied to reactants in order to cross the energy barrier and thus convert to products.
A catalyst is a substance which increases the rate of a reaction by taking the reaction through a different path which involves lower activation energy and thus more molecules can cross the energy barrier and convert to products.
The catalyst itself does not take part in the chemical reaction and is regenerated as such at the end.
percent composition?: 85.05 g of Mg combines completely with 112.21 g of S.
empirical formula?: 78.8% C, 20.2% H. 67.6% Hg, 10.8% S, 21.6% O
Empirical Formula = C20 H60 HG1 S1 O4 (numbers should be in subscript)
Percent Composition =
MG = 43%
S = 56.8%
A substance did not change its chemical nature in a reaction. Which most likely describes the reaction?
A) It was heated.
B) It was hit with a hammer.
C) It was placed in a salt solution.
D) It was frozen.
The correct answer is D
Answer:
It was frozen.
Explanation:
A substance may undergo any chemical change in its nature in all the given cases except when it is frozen.
A) during heating there is chances that it undergoes decomposition . Like if calcium carbonate is heated it converts to calcium oxide and carbon dioxide.
B) When a compound is hit with a hammer there is chance of its chemical decomposition.
C) If a compound is placed in a salt solution it may react with the salt or water.
D) However freezing is purely a physical process, where contact with any other compound or any chance of chemical decomposition is not possible.
Your BAC level depends on
Drinking one standard drink will increase your BAC by about 0.02 (remember this can depend on the factors mentioned above). As your BAC rises, so does your risk of being involved in a crash. This is why drivers with an open licence have to keep under a BAC of 0.05.
If you designed your own experiment to prove the law of conservation of mass, what conditions would be required?
Water is unique because the density of it's solid is less than the density of it's liquid. Describe how life would be different if this weren't true
Ice caps would float therefore providing insulation for aquatic life and ensuring they do not freeze due to the cool temperature.
how many grams of CO2 are in 2.1 moles of the compound
Answer: Chemical Reactions, Acids, and Bases Unit Test
1. 24 mL of Mg burn in 32mL O2 to produce 56 mL of MgO
2. 92.4
3. Bonds of the reactants are broken, and bonds of the products are formed
4. The reaction rate decreases
5. in chemical equilibrium
6. The equilibrium shifts to the right and more products are formed
7. the I ion and the positive end of a water molecule
8. Less than 0 degree Celsius
9. Greater than
10. Solubility
11. feels slippery
12. MgCl2 and H2O
13. accept a proton and become NH4+
14. stay about the same
15. electrolyte
These are the answers I put for the short answers:
16. The double-replacement is KBr+. The resulting compound is AgNO3+AgBr
17. The ion that is formed is Br. The bromine gets reduced
18. Buffer solution is a solution that is resistant to large changes in pH
19. The peaks are called the activation energy. It is energy used to get the reaction going.
20. It is supersaturated
21. According to the figure above detergent is a base
Part 2: These are the answers that I put as well
1. 4Fe+3O2=2Fe2O3 3:2
2. 1.31M
3. 300mg of water
4. 60.46 kJ would be absorbed during the reaction
What is the wavelength of an earthquake wave if it has a speed of 15 km/s and a frequency of 15 Hz?
Each body cell in the American black bear has "74" chromosomes. How many chromosomes are in the black bears sex cells bears?
Explain your answer
Answer: (2) Black bears have 74 chromosomes and 37 haploid chromosomes. (3) The bears become s3xually mature anywhere from 3-7 years. (4) There are two types of reproductive barriers: Prezygotic and Postzygotic.
Explanation:
37 chromosomes are in the black bears sex cells bears,Sex cells only contain half the number of chromosomes found in the body cells.
What is meant by Chromosomes?Chromosomes are the thread-like structure present in the nucleus of plant and animal cells. Chromosomes are the vehicle that carries DNA (the genetic material of the cell) wrapped around by the histone proteins.A chromosome is a DNA molecule that consists of a part or all of the genetic material of an organism. The chromosome is present in the nucleus of each cell, and it is packaged into thread-like structures. Structurally, each chromosome is composed of DNA that is tightly coiled around special proteins called histones.The main function of chromosomes is to carry the genetic material from one generation to another.The body cell of an American black bear contains 74 chromosomes, then each sex cell contains 37 chromosomes.
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Consider the chemical reaction in equilibrium.
H2 + I2 + heat ⬄ 2HI
What will happen to the chemical equilibrium if the temperature of the system is increased?
A)The direction of the chemical equilibrium will shift to the right, favoring the forward reaction.
B)The chemical equilibrium will not be affected by an increase in temperature. C)The direction of the chemical equilibrium will shift to the left, favoring the reverse reaction.
D) The chemical equilibrium will be lost permanently with a change of temperature.
A) The chemical equilibrium will shift to the right, favoring the forward reaction.
ExplanationThe forward reaction absorbs heat. It is endothermic. Going in that direction will remove heat from the system. The temperature of the system will drop.
The reverse reaction produces heat. It is exothermic. Converting products back to reactants will adds to the heat of the system. The temperature of the system will increase.
By the Le Chatelier's Principle, a system in equilibrium will respond to changes in a way that minimizes their effect.
In this question, the change is an increase in temperature. The system will seek to reduce its temperature. It will favor the forward reaction, which is endothermic and removes heat from the system.
Temperature of the system will decrease. There will be more products and less reactants. The equilibrium will shifts to the left.
The chemical equilibrium will shift to the right, favouring the forward reaction. Hence, option A is correct.
What is chemical equilibrium?Chemical equilibrium is the condition in the course of a reversible chemical reaction in which no net change in the amounts of reactants and products occurs.
The forward reaction absorbs heat. It is endothermic. Going in that direction will remove heat from the system. The temperature of the system will drop.
The reverse reaction produces heat. It is exothermic. Converting products back to reactants will add to the heat of the system. The temperature of the system will increase.
By Principle, a system in equilibrium will respond to changes in a way that minimizes their effect.
In this question, the change is an increase in temperature. The system will seek to reduce its temperature. It will favour the forward reaction, which is endothermic and removes heat from the system.
The temperature of the system will decrease. There will be more products and fewer reactants. The equilibrium will shift to the left.
Hence, option A is correct.
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Which of the following is an accurate example of how the water cycle can influence local weather? A. An increase in evaporation rates along a coastal area leads to afternoon thunderstorms. B. Water in a lake soaks into the local groundwater system. C. An increase in an area's precipitation causes the area to experience a drought. D. all of these
The answer is; A
During a hot day, the land heats up faster than the waters. The air on land becomes warm and less dense fast and begin to rise in the atmosphere. The air on the ocean with is still cooler and denser moves in to replace the rising on land air. This causes a sea breeze. The sea breeze carries with it, moisture. The hotter the day the higher the humidity. When the air goes inland, it causes precipitation when it rises, cool, and condenses.
Answer:
I got it Right
Explanation:
In Study Island