Thermochemistry and Energetics of Chemical Reactions MCQs

Question 1

Consider the reaction pathways shown below, According to Hess's Law, the enthalpy change, in kJ mol , for reaction X is:

Accepted Answer

-111 kJ/mol

Answer

+111 kJ/mol

Answer

-677 kJ/mol

Answer

+677 kJ/mol

Question 2

A 100g sample of water at 25 °C and 1 atm. of pressure. Then, 100g of water that has recently heated to 100 °C from 0 °C and then cooled to 25 °C at 1 atm. of pressure.

Accepted Answer

Has the same internal energy

Answer

Has more internal energy

Answer

Has less internal energy

Answer

None of these

Question 3

If a system loses 250 kJ of heat at the same time that it is doing 500 kJ of work, what is the change in the internal energy of the system?

Accepted Answer

-750 kJ

Answer

+250 kJ

Answer

-250 kJ

Answer

+750 kJ

Question 4

If 1 J of heat is added to a 2.00 g sample of aluminum metal, and the temperature of the metal increases by 1°C, what is the specific heat of aluminum?

Accepted Answer

0.5 J/g°C

Answer

1 J/g°C

Answer

2 J/g°C

Answer

None of the above

Question 5

Water has a specific heat of 4.184 J/g deg while glass (Pyrex) has a specific heat of 0.780 J/g degree. If 10.0 J of heat is added to 1.00 g of each of these, which will experience the larger increase in temperature?

Accepted Answer

Glass

Answer

Water

Answer

They both will experience the same change in temperature since only the amount of substance relates to the increase in temperature

Answer

None

Question 6

The heat of combustion for 1 mole of carbon to carbon dioxide is -410 kJ. How many kJ of heat would be liberated from the complete combustion of 60.0 g of carbon?

Accepted Answer

-2050 kJ

Answer

-82 kJ

Answer

-24,600 kJ

Answer

None

Question 7

Given the following data at 1 atm of pressure and 25.0 °C...ΔH°formation = +64.4 kJ/mole for Cu²⁺.ΔH°formation = -152.4 kJ/mole for Zn²⁺.ΔH°formation = 0 for both Zn and Cu²⁺ because these are in the most stable state.Calculate the standard heat of reaction for........Zn(s) + Cu2+ (aq) →Zn2+(aq) + Cu(s)

Accepted Answer

-217 kJ/mole

Answer

+217 kJ/mole

Answer

-88.0 kJ/mole

Answer

+88.0 kJ/mole

Question 8

Which statement describes characteristics of an endothermic reaction?

Accepted Answer

The sign of ΔH is positive, and the products have more potential energy than the reactants.

Answer

The sign of ΔH is positive, and the products have less potential energy than the reactants.

Answer

The sign of ΔH is negative, and the products have less potential energy than the reactants.

Answer

The sign of ΔH is negative, and the products have more potential energy than the reactants.

Question 9

Given the following information, calculate the heat of formation of C₂H4Cl₂(g) in kJ/mole:2 C(s) + 2 H₂(g) + Cl₂(g) → C₂H4Cl₂(g)2 C(s) + 2 H₂(g) → C₂H4(g) ΔH°/kJ = +52.3kJC₂H4Cl₂(g) → Cl₂(g) + C₂H4(g)ΔH°/kJ = +116kJ

Accepted Answer

+64

Answer

-64

Answer

-168

Answer

+168

Question 10

Calculate the value of ΔH°/kJ for the following reaction using the listed thermochemical equations:N₂(g) + 1/2O₂(g)→N2O(g)2NH₃(g) + 3N2O(g)→4N₂(g) + 3H₂O(l), ΔH°/kJ = -1010kJ4NH₃(g) + 3O2(g)→2N₂(g) + 6H₂O(l), ΔH°/kJ = -1531kJ

Accepted Answer

+81.5

Answer

-81.5

Answer

+163

Answer

-163

Question 11

Use the given the standard enthalpies of formation to determine the heat of reaction of the following reaction:2 Ag₂S(s) + 2 H₂O (l) → 4 Ag(s) + 2 H₂S(g) + O₂(g)ΔH°f Ag₂S(s) = -33 kJ/moleΔH°f H2S(g) = -21 kJ/moleΔH°f H₂O(l) = -286 kJ/mole

Accepted Answer

+596 kJ

Answer

+232.4 kJ

Answer

+423.5 kJ

Answer

+518.0 kJ

Question 12

Use the given standard enthalpies of formation to determine the heat of reaction of the following reaction:2 LiOH(s) + CO₂(g) → Li₂CO₃(s) + H₂O(l)ΔH°f LiOH(s) = -487 kJ/moleΔH°f Li₂CO₃(s) = -1216 kJ/moleΔH°f H₂O(l) = -286 kJ/moleΔH°f CO₂(g) = -394 kJ/mole

Accepted Answer

-134 kJ

Answer

-198.6 kJ

Answer

+198.6 kJ

Answer

+133.5 kJ

Question 13

Use the given standard enthalpies of formation to determine the heat of reaction of the reaction:C3H6O(l) + 4O2(g) → 3 CO2(g) + 3 H2O(l)ΔH°f CO2(g) = -394 kJ/moleΔH°f H2O(l) = -286 kJ/moleΔH°f C3H6O(l) = -250 kJ/mole

Accepted Answer

-1790 kJ

Answer

-1566 kJ

Answer

-1285 kJ

Answer

-1856 kJ

Question 14

Use the following bond energies to calculate ΔH°f or the given reaction.(H - C = 414; C - C = 347; C - C = 619; H - H = 435).CH2 = CH2(g) +H2(g) → CH3 - CH3(g)

Accepted Answer

-121 kJ/mol

Answer

-92 kJ/mol

Answer

-55 kJ/mol

Answer

-102 kJ/mol

Question 15

The branch of physical chemistry which deals with the quantities of heat absorbed or evolved during a chemical reaction is called:

Accepted Answer

Thermochemistry

Answer

Thermodynamics

Answer

Calorimetry

Answer

None of the above

Question 16

The study of general laws governing the process which involve heat changes, and the conservation of energy is called:

Accepted Answer

Thermodynamics

Answer

Thermo chemistry

Answer

Conductometry

Answer

None of the above

Question 17

Which of the following is applicable for a thermo chemical reaction?

Accepted Answer

It tells whether a reaction is exothermic or endothermic.

Answer

It tells about the physical state of the reactants and products.

Answer

It tells about the allotropic forms of the reactant.

Answer

It tells whether a particular reaction is possible or not.

Question 18

An exothermic reaction is one which:

Accepted Answer

Is accompanied by evolution of heat.

Answer

Takes place on heating.

Answer

Is accompanied by a flame.

Answer

Is accompanied by absorption of heat.

Question 19

An endothermic reaction is one in which:

Accepted Answer

Heat is absorbed.

Answer

Heat is converted into electricity.

Answer

Heat is evolved.

Answer

Heat is converted into mechanical work.

Question 20

An exothermic reaction is one in which the reacting substances:

Accepted Answer

Have more energy than the products.

Answer

Have less energy than the products.

Answer

Have the same energy as the products.

Answer

Are at a higher temperature than the products.

Free Thermochemistry and Energetics of Chemical Reactions MCQs with Answers