Prince George Community College » Chemistry » Chem 1010 - General Chemistry 1 » Fall 2021

Chem 1010 - General Chemistry 1 » Fall 2021 » CH4 Energy and Chemical Reactions

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Question #1

Which statement describes an example of change in potential energy?

A. A candy bar is metabolized by your body

B. Molecules moving through a liquid

C. Slowing a car by depressing the brakes

D. Ions moving through a solution toward an oppositely charge electrode

Question #2

Convert 23.2 kJ to Cal.

A. 9.7×104 Cal

B. 5.5 Cal

C. 5.5×103 Cal

D. 97 Cal

Question #3

If you leave a 30-g silver spoon that was initially at 40 °C in a 250 mL drink at 50 °C for five minutes, what is likely to happen?

A. Nothing will happen.

B. The spoon and the drink will have the same temperature.

C. The spoon will get cooler.

D. The drink will get cooler, but the spoon will remain at the same temperature.

Question #4

Which equation states the law of conservation of energy?

A. w = PΔV

B. E = mc2

C. ΔE = q + w

D. E = 1/2 mv2

Question #5

The total internal energy of the system depends on

A. temperature, type of particles and number of particles present

B. only the number of particles present.

C. only the temperature.

D. only the type of particles.

Question #6

Choose the process that requires the most energy when the temperature of 23.4 g ice at -25.0 °C is raised to 37.0 °C.

A. Warming the ice to 0.0 °C

B. All of the processes require essentially the same amount of energy.

C. Melting the ice

D. Warming the water

Question #7

An electric heater is used to supply 36.3 J of energy to a 21.0-g graphite block with an initial temperature of 20.3 °C. Determine the final temperature of the graphite. (Specific heat of graphite = 0.72 J/g °C.)

A. 18 °C

B. 2.4 °C

C. 23 °C

D. 1079 °C

Question #8

Which one of these processes is exothermic?

A. Freezing ice cubes

B. melting butter

C. Microwaving popcorn

D. Photosynthesis

Question #9

Define the term "enthalpy change."

A. Heat transfer at constant temperature

B. Heat transfer at constant volume

C. Heat transfer at constant pressure

D. Heat transfer with volume and pressure varying

Question #10

What is the correct standard thermochemical expression for the formation of H2O by burning H2 and O2?

A. H2O(l) → 2 H2(g) + O2(g) ΔH° = -285.8 kJ

B. H2(g) + ½ O2(g) → H2O(l) ΔH° = -285.8 kJ

C. H2(g) + ½ O2(g) → H2O(g) ΔH° = -285.8 kJ

D. 2 H2(g) + O2(g) → 2 H2O(g) ΔH° = -285.8 kJ

Question #11

It takes about 41.84 J of energy to raise the temperature of 10.0 g water from 23.4 to 24.4 °C. If we place 10.0 g water at 23.0 °C into a refrigerator at 6.0 °C, calculate how many joules of energy are transferred from the water to the refrigerator

A. 711 J

B. 251 J

C. 377 J

D. 962 J

Question #12

Choose the molecule that has the weakest chemical bond, based on this data: Bond Bond Enthalpy (kJ/mol) H–F 566 H–Cl 431 H–Br 366 H–I 299

A. HBr

B. HF

C. HCl

D. HI

Question #13

When a 6.49-g sample of CaCl2 dissolves in 250 g water in a coffee cup calorimeter, the temperature rises from 22.0 to 26.6 °C. Calculate the change in enthalpy for this solution-making process. Express your answer in kilojoules per mole of salt. (Assume the solution has a density of 1.00 g/mL and specific heat of 4.184 J/g°C.)

A. -534 kJ/mol

B. 82.3 kJ/mol

C. 0.0434 kJ/mol

D. -82.3 kJ/mol

Question #14

Copper is a good heat-transfer material. How much heat must be absorbed from 0.500 kg copper to change its temperature from 26.0 °C to -63.0 °C? The specific heat capacity (Cu) = 0.385 J/g °C.

A. -186 J

B. 1.30 J

C. 1.71×104 J

D. 17.1 J

Question #15

The standard enthalpy of formation of KCl(s) is -436.7 kJ/mol, and the standard enthalpy of formation of KCl(aq, 1m) is -419.5 kJ/mol. Determine the standard enthalpy of solution of KCl.

A. -402.3 kJ/mol

B. +856.2 kJ/mol

C. +17.2 kJ/mol

D. +856.2 kJ/mol

E. -17.2 kJ/mol

Question #16

Choose the correct chemical equation related to the standard enthalpy of formation of (CH3)3N.

A. 6 C(s, graphite) + 9 O2(g) + H2(g) + N2(g) → 2 (CH3)3N(l)

B. 2 (CH3)3N(l) → 12 C (s, graphite) + 6 H2(g) + N2(g)

C. 4 (CH3)3N(l) + 21 O2(g) → 12 CO2(g) + 18 H2O(l) + 2 N2(g)

D. 3 C(s, graphite) + 9/2 H2(g) + 1/2 N2(g) → (CH3)3N(l)

Question #17

Calculate the heat of combustion of propane according to the equation below. C3H8(g) + 5 O2(g) → 3 CO2(g) + 4 H2O(l)

A. -783.1 kJ/mol

B. -103.8 kJ/mol

C. -2219.9 kJ/mol

D. -2427.5 kJ/mol

Question #18

A cheese pizza contains 10.2 g fat/100 g. Calculate the percentage of BMR (= 1750 Cal/day) available from the fat in a 400-g cheese pizza.

A. 21 %

B. 0.58 %

C. 41 %

D. 5.2 %

Question #19

Coal is a common fuel used for heating and cooking in many parts of the world. Calculate the fuel value of coal (assume that coal is pure graphite).

A. 65.53 kJ/g

B. -393.5 kJ/mol

C. 4.726 x 103 kJ/g

D. 32.76 kJ/g

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