Chemistry - Thermo HW1 - Energy Fill in the answers to …chemleal.com/attachments/File/ChemPDFs/Worksheets/Unit_7_WS_Packet...Chemistry - Thermo HW1 - Energy Fill in the answers to

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Chemistry - Thermo HW1 - Energy Fill in the answers to the following questions.

Name: ________________________ Date: _______________ Per: ________

1. The flow of energy due to a difference in the average kinetic energy is known as _____________.

2. The measure of the random motions (average kinetic energy) of the components (parts) or a

substance is known as _________________.

3. The ability to do work or produce heat is known as ____________.

4. The energy an object has due to its position or composition is known as ______________.

5. The energy an object has due to its motion is known as ______________.

6. The part of the universe that we focus attention is known as the _______________.

7. The part of the universe that influences what we are focused on is known as ____________.

8. If you have a beaker filled with ice and you want to see what happens to the ice when you add salt,

the ice and salt would be classified as the _______________.

9. If you have a beaker filled with ice and you want to see what happens to the ice when you add salt,

the beaker would be classified as the _______________.

10. When a reaction causes energy to leave a system and go out to the surroundings, the reaction can be

classified as __________________.

11. When a reaction causes energy to enter a system from the surroundings, the reaction can be

classified as __________________.

12. The graph below represents an ________________ reaction because___________________.

Word Bank:

Endothermic, potential energy, surrounding, energy, kinetic energy, temperature, system

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Chemistry - Thermo HW2 - Energy Flow and Thermodymics

Name: ________________________ Date: _______________ Per: ________

Please show all needed work

1. The first law of ______________ states that the energy of the universe is constant.

2. Heat is typically measured in units of: _________________.

3. SI units for specific heat capacity are: _________________.

4. Perform the indicated conversion: 2.60 103 cal = _______________ J

5. 2134.95 J of energy is equivalent to how many calories?

6. In the equation E = q + w, the q stands for ______________.

7. In the equation E = q + w, the w stands for ______________.

8. Calculate E given the following information: q = +41 kJ, w = +11 kJ

9. A gas absorbs 75 kJ of heat and does 27 kJ of work. Calculate E.

10. A system absorbs 159 kJ of heat, and performs 87 kJ of work on the surroundings. What is E of the system?

Bank: work, heat, thermodynamics, joules, 72, 1.09 104 , 48, 52, 510.265

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Chemistry - Thermo HW3 - Specific Heat

Name: ________________________ Date: _______________ Per: ________

1. For problems that involve calculating energy requirements, the equation is Q = m ( T) Cp. The

variable Q stands for _________________ and is measured in units of ____________.

2. For problems that involve calculating energy requirements, the equation is Q = m ( T) Cp. The

variables m, T, and Cp stand for:

m: ________________________

T: _______________________

Cp: _______________________

3. The amount of energy needed to raise the temperature of one gram of a substance by one Celsius

degree is known as _____________________.

4. The amount of energy needed to raise the temperature of one gram of water by one Celsius degree is

known as _____________________.

5. For problems that involve calculating energy requirements, the equation is Q = m ( T) Cp. How

would you isolate to solve for T?

Word Bank: calorie, joules, energy, specific heat capacity, mass, change in temperature

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Chemistry - Thermo HW4 - Thermo Calculations

Name: ________________________ Date: _______________ Per: ________

Please show all needed work. Write answers on the line or the space provided.

1. The amount of heat energy released or absorbed in a process is known as the

___________________.

2. When 1 mole of methane, CH4, is burned, 890 kJ of energy is released. Calculate the H when

48 grams of CH4 is burned. (Hint: determine if the reaction is endothermic or exothermic)

Answer: ___________________

3. The molar heat of fusion of water is about 6 kJ/mol. How much energy is needed to convert 72

grams of ice at 0 C to water at 0 C ?

Answer: ___________________

4. The amount of energy needed to heat 2 g of metal from 10oC to 60

oC is 700 J. The specific heat

capacity of this sample of metal is ___________.

5. A sample of metal has a specific heat of 0.2 J/g C. If 800 J of energy is added to and it results

in a temperature change of 20 C, determine the mass of the metal.

Answer: _________________

6. A 10 gram sample of metal with a specific heat of 0.50 J/g C is heated with 115 J of energy.

How many degrees C does the temperature change?

Answer: ___________________

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7. You have a piece of iron metal and you added energy to it by heating it. You wait until the metal

reaches a stable temperature and then transfer it to a known volume of water. The known

volume of water is at a temperature lower than that of the metal. Describe what will happen to

the temperature of both the water and the metal. Also, describe how you would determine how

much energy you added to the metal.

Bank: 200, 24, enthalpy, 23, 7, -2670

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Name _______________________________________ Per ____ Calculations involving Specific Heat

Tmq

cp Δ⋅=

Standard: Students know how to solve problems involving heat flow and temperature changes, using known values of specific heat and latent heat of phase change.

Tmcq p Δ⋅⋅=

Specific heat is the energy required to increase the temperature of one gram of a substance by one degree Celsius. Metals have a characteristically low specific heat (little energy is required to increase their temperature). Water has a VERY HIGH specific heat (a lot of energy is required to increase its temperature).

Gold has a specific heat of 0.129 J/(g⋅°C). How many joules of heat energy are required to raise the temperature of 10 grams of gold from 22 °C to 32 °C?

An unknown substance with a mass of 45 grams absorbs 1500 J while undergoing a temperature increase of 100 °C. What is the specific heat of the substance?

How much energy must be absorbed by 50 grams of water in order to raise the temperature by 20°C? The specific heat of water is on your periodic table.

A 25 gram piece of graphite must absorb 710 J in order to raise the temperature of the graphite from 20 °C to 60 °C. What is the specific heat of graphite?

Copper has a specific heat of 0.385 J/(g⋅°C). How much energy does a 0.5 gram piece of copper give off as its temperature cools from 55 °C to 15 °C?

80 grams of an unknown substance undergoes a temperature increase of 15 °C after absorbing 600 Joules. What is the specific heat of the substance?

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Name ________________________

Calorimetry Worksheet-1 1. What is the number of calories needed to change the temperature of 50.0 g of water 15.0

oC?

2. How many calories are needed to increase the temperature of 150.0 g water from 40.0oC to

65.0oC?

3. What temperature in oC is produced when 800.0 calories is absorbed by 100.0 g water?

4. How many grams of water can be heated from 20.0 oC to 75

oC using 12500.0 Joules?

5. How many kilocalories are required to change the temperature of 300.0 grams of 0oC water to

40.0oC?

6. What is the final temperature after 80.0 calories is absorbed by 10.0g of water at 25.0oC?

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Calorimetry Worksheet-2

1. The specific heat of aluminum is 0.900 J/g

oC.

a. How much energy is needed to raise the temperature of a 8.50 x 102g block of

aluminum from 22.8oC to 94.6

oC?

b. What is the specific heat of aluminum in Joules per mole degree Celcius?

2. In a coffee-cup calorimeter, 100.0 mL of 1.0 M NaOH and 100.0 mL of 1.0 M HCl are mixed.

Both solutions were originally at 24.6 oC. After the reaction, the temperature is 31.3

oC. What is

the enthalpy change for the neutralization of HCl by NaOH?

3. A swimming pool, 10.0 m by 4.0 m is filled to a depth of 3.0 m with water at a temperature of

20.2 oC. How much energy is required to raise the temperature of the water to 30.0

oC?

4. A 75.5 kg student at a temperature of 36.6 oC jumps into a hot tub containing 160,000 mL of

water on a cold winter’s day. The water, which is initially at a temperature of 39.856 oC, cools

down to a temperature of 38.652 oC and oddly enough, the student warms up to that same

temperature after a 35 minute soak. Calculate the specific heat of the student, assuming that no

heat is lost in the exchange.

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Change in Phase – Water

This diagram assumes the condition of 1 atmosphere pressure.

Leg “A”: Ice is heated from -20 °C to 0 °C Ice cools from 0 °C to -20 °C Leg ”B”: At 0 °C ice melts to form liquid water; temperature remains constant during a phase change; energy required is called heat of ____________________ At 0 °C liquid water freezes to form ice; temperature remains constant during a phase change Leg “C”: Liquid water is heated from 0 °C to 100 °C Liquid water cools from 100 °C to 0 °C Leg ”D”: At 100 °C water vaporizes to form water vapor; temperature remains constant during a phase change; energy required is called heat of ___________________ At 100 °C water vapor condenses to form liquid water; temperature remains constant during a phase change Leg “E”: Water vapor is heated from 100 °C Water vapor is cooled to 100 °C

Key Concepts:

1. Phase changes going from left to right ( ) , including melting and vaporizing, require the absorption of energy (heat).

2. Phase changes going from right to left ( ), including freezing and condensation, involve the removal of energy.

3. Temperature remains constant during a phase change.

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Phase Diagram for Water

Definitions: ______________________________ Phase change from solid to liquid

______________________________ Phase change from liquid to solid

______________________________ Phase change from liquid to gas

______________________________ Phase change from gas to liquid

______________________________ Phase change from solid to gas

______________________________ Phase change from gas to solid

______________________________ Point where all three phases exist at the same time in equilibrium (this is 4.58 torr and 0.0098 °C for water) ______________________________Temperature at which a substance melts at 1 atm pressure

______________________________Temperature (Tc) above which substances cannot exist as solids or liquids ______________________________ Pressure (Pc) above which substances cannot exist as gases

______________________________ Point identified by the Tc and Pc Key Concepts:

1. Phase changes going from left to right ( ) , including melting, vaporization, and sublimation, require the absorption of energy (heating).

2. Phase changes going from right to left ( ), including freezing, condensation and deposition, involve the removal of energy (cooling).

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Chemistry - Equilibrium HW1 - Kinetics

Name: __________________________________ Date: _____________ Per: _____

1. The ____________ model explains why a reaction proceeds faster if the concentrations of the

reacting molecules are increased.

2. True or false? A catalyst is a substance that speeds up a reaction without being consumed.

A) True B) False

3. True or false? A minimum energy called the activation energy is needed for a reaction to occur.

A) True B) False

4. True or false? At equilibrium, the concentrations of all reactants and products are constant.

A) True B) False

5. True or false? At equilibrium, the concentrations of all reactants and products are equal.

A) True B) False

6. Collisions need to have _______________ and _______________ for a reaction to occur.

7. Reaction rates can measure the disappearance of reactants and are stoichiometrically proportional.

A) True B) False

8. All of the following are factors affecting the rate of a chemical reaction except _____________.

A) temperature D) concentration

B) surface area E) volume

C) presence of a catalyst

9. Increasing the surface area _____________ the rate of a chemical reaction because it

_________________.

10. Reaction rates depend on factors such as ___________________, _________________, and

___________________.

Bank: pressure, increases, collision, temperature, concentration

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Chemistry - Equilibrium HW2 - Keq

Name: ______________________________ Date: _______________ Per: _____

1. Consider the general reaction: jA + kB lC + mD

Write the correct equilibrium expression below.

2. Choose the correct equilibrium expression for the following reaction.

2A(s) + 3B(l) C(aq) + 4D(aq)

A)

2 3

4

[A] [B]

[C][D] B) [C] [D]

4 C)

4

2 3

[C][4D]

[2A] [3B] D)

4

2 3

[C][D]

[A] [B] E) none of these

3. Write the equilibrium expression for the reaction

3O2(g) 2O3(g)

4. For the reaction: F2(g) 2F(g)

at a particular temperature, the concentrations at equilibrium were observed to be [F2] = 1.6 10–2

mol/L and [F] = 2.0 10–4

mol/L. Calculate the value of the equilibrium constant (Keq) from these

data. (The units are deleted.)

5. For the reaction: 2NO(g) + O2(g) 2NO2(g)

at a certain temperature, the equilibrium concentrations were found to be [NO2] = 2.8 10–3

M,

[O2] = 1.0 10–2

M,and [NO] = 2.0 10–3

M. Calculate the value of the equilibrium constant

(Keq) from these data (delete units).

6. For the reaction: CO(g) + H2O(g) CO2(g) + H2(g)

K = 3.88 at a certain temperature. If at this temperature in a certain experiment the equilibrium

concentrations are [H2] = 1.4 M, [CO2] = 1.8 M, and [H2O] = 0.26 M, calculate [CO].

7. For the reaction: 2SO2(g) + O2(g) 2SO3(g)

at a certain temperature, the equilibrium concentrations were observed to be [SO2] = 0.581 M, [O2]

= 7.50 10–2

M, and [SO3] = 0.650 M. Calculate the value of K for this system at this temperature.

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Chemistry - Equilibrium HW3 - Le Chatelier and Ksp

Name: ___________________________ Date: _______________ Per: ____

Use the following to answer questions 1-4:

Consider the reaction 2H2(g) + O2(g) 2H2O(g) at some equilibrium position. Using the following

choices, indicate what will happen if the changes below are made.

a. shifts to the left

b. shifts to the right

c. no change

1. Additional H2O(g) is injected into the reaction vessel.

2. Some H2(g) is removed from the reaction vessel.

3. The size of the reaction vessel is decreased.

4. Some He(g) is injected into the reaction vessel.

Use the following to answer questions 5-9:

Consider the reaction system CH4(g) + 2O2(g) CO2(g) + 2H2O(g) + energy, and use the following

choices to describe what happens when the changes below are made to the system at equilibrium.

a. shifts to the left

b. shifts to the right

c. no change

5. O2(g) is removed from the reaction vessel.

6. CO2(g) is removed from the reaction vessel.

7. He(g) is added to the reaction vessel.

8. The temperature is increased.

9. CH4(g) is added to the reaction vessel.

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Use the following to answer questions 10-12:

Given the equation A(g) B(g) + 2C(g). At a particular temperature, K = 1.4 105.

10. Addition of chemical B to an equilibrium mixture of the above

A) will cause [A] to increase D) cannot be determined

B) will cause [C] to increase E) none of the above

C) will have no effect

11. Placing the equilibrium mixture in an ice bath (thus lowering the temperature)

A) will cause [A] to increase D) cannot be determined

B) will cause [B] to increase E) none of the above

C) will have no effect

12. Raising the pressure by decreasing the volume of the container

A) will cause [A] to increase D) cannot be determined

B) will cause [B] to increase E) none of the above

C) will have no effect

13. Given the solubility products (Ksp)

BaSO4 1.5 10-9

CoS 5.0 10-22

PbSO4 1.3 10-2

AgBr 5.0 10-13

which of the following compounds is the most soluble (in mol/L)?

A) BaSO4 B) CoS C) PbSO4 D) AgBr E) BaCO3

14. Write the balanced equation for the dissolving of Ag2S(s) in water.

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