Quiz about Dok Energetics Questions

Question 1

Which is correct when Ba(OH)₂ reacts with NH₄Cl?

Accepted Answer

C

Answer

A

Answer

B

Answer

D

Question 2

5.35g of solid ammonium chloride, NH₄Cl(s), was added to water to form 25.0g of solution. The maximum decrease in temperature was 14 K. What is the enthalpy change, in kJmol^-1, for this reaction? (Molar mass of NH₄Cl = 53.5gmol^-1; the specific heat capacity of the solution is 4.18 Jg^-1K^-1)

Accepted Answer

C

Answer

A

Answer

B

Answer

D

Question 3

Which combination is correct for the standard enthalpy change of neutralization?

Accepted Answer

A

Answer

B

Answer

C

Answer

D

Question 4

The same amount of heat energy is added to 1.00 g of each substance. Which statement is correct if all the substances are at the same temperature before the heat energy is added?

Accepted Answer

Copper will reach the highest temperature.

Answer

Water will reach the highest temperature.

Answer

All four substances will reach the same temperature.

Answer

Aluminium will reach a higher temperature than sodium chloride.

Question 5

Which statement is correct for the reaction with this enthalpy level diagram?

Accepted Answer

Heat energy is absorbed during the reaction and the reactants are more stable than the products.

Answer

Heat energy is released during the reaction and the reactants are more stable than the products.

Answer

Heat energy is released during the reaction and the products are more stable than the reactants.

Answer

Heat energy is absorbed during the reaction and the products are more stable than the reactants.

Question 6

The table shows information about temperature increases when an acid and an alkali are mixed. What is the value of y?

Accepted Answer

x

Answer

12x

Answer

2x

Answer

4x

Question 7

Which processes are exothermic?

Accepted Answer

I and III only

Answer

I and II only

Answer

II and III only

Answer

I, II and III

Question 8

Which ionic compound has the most endothermic lattice enthalpy?

Accepted Answer

Magnesium oxide

Answer

Sodium chloride

Answer

Sodium oxide

Answer

Magnesium chloride

Question 9

Which process is endothermic?

Accepted Answer

B

Answer

A

Answer

C

Answer

D

Question 10

Which reaction has an enthalpy change equal to the standard enthalpy change of combustion?

Accepted Answer

B

Answer

A

Answer

C

Answer

D

Question 11

Which combination is correct for the exothermic reaction that occurs between zinc and copper sulfate solution.

Accepted Answer

C

Answer

A

Answer

B

Answer

D

Question 12

Which process is endothermic?

Accepted Answer

C

Answer

A

Answer

B

Answer

D

Question 13

Which processes have a negative enthalpy change?

Accepted Answer

I, II and III

Answer

I and II only

Answer

I and III only

Answer

II and III only

Question 14

Which statement is correct given the enthalpy level diagram below?

Accepted Answer

The reaction is exothermic and the products are more thermodynamically stable than the reactants.

Answer

The reaction is endothermic and the products are more thermodynamically stable than the reactants.

Answer

The reaction is endothermic and the reactants are more thermodynamically stable than the products.

Answer

The reaction is exothermic and the reactants are more thermodynamically stable than the products.

Question 15

Identical pieces of magnesium are added to two beakers, A and B, containing hydrochloric acid. Both acids have the same initial temperature but their volumes and concentrations differ. Which statement is correct?

Accepted Answer

The maximum temperature in A will be higher than in B.

Answer

The maximum temperature in A and B will be equal.

Answer

It is not possible to predict whether A or B will have the higher maximum temperature.

Answer

The temperature in A and B will increase at the same rate.

Question 16

Which is correct about energy changes during bond breaking and bond formation?

Accepted Answer

C

Answer

A

Answer

B

Answer

D

Question 17

Which processes are exothermic?

I. Ice melting

II. Neutralization

III. Combustion

Accepted Answer

II and III only

Answer

I and II only

Answer

I and III only

Answer

I, II and III

Question 18

Which is true for a chemical reaction in which the products have a higher enthalpy than the reactants?

Accepted Answer

A

Answer

B

Answer

C

Answer

D

Question 19

Some water is heated using the heat produced by the combustion of magnesium metal. Which values are needed to calculate the enthalpy change of reaction?

I. The mass of magnesium

II. The mass of the water

III. The change in temperature of the water

Accepted Answer

I, II and III

Answer

I and II only

Answer

I and III only

Answer

II and III only

Question 20

What is the energy, in kJ, released when 1.00 mol of carbon monoxide is burned according to the following equation?
$$2CO(g)+O_2(g)\ →\ 2CO_2(g):\ ΔH^Θ=−564kJ$$

Accepted Answer

282

Answer

141

Answer

564

Answer

1128

Question 21

The specific heat of iron is 0.450Jg^-1K^-1 . What is the energy, in J, needed to increase the temperature of 50.0 g of iron by 20.0 K?

Accepted Answer

450

Answer

9.00

Answer

22.5

Answer

45.0

Question 22

Which of the following reactions are exothermic?

Accepted Answer

I and II only

Answer

I and III only

Answer

II and III only

Answer

I, II and III

Question 23

Consider the following two equations.
$$2Ca(s)+O_2(g)→2CaO(s)$$
$$ΔH^Θ=+x\ kJ$$

$$Ca(s)+0.5O_2(g)+CO_2(g)→CaCO_3(s)$$
$$ΔH^Θ=+y\ kJ$$

What is the enthalpy change, in kJ, for the following reaction?
$$CaO(s)+CO_2(g)→CaCO_3(s)$$

Accepted Answer

y - 0.5x

Answer

y - x

Answer

0.5 - y

Answer

x - y

Question 24

Using the equations below:
$$C(s)+O_2(g)→CO_2(g):\ ΔH^Θ=−390kJ$$
$$H_2(g)+\frac{1}{2}O_2(g)→H_2O(l):ΔH^Θ=−286kJ\ $$
$$CH_4(g)+2O_2(g)→CO_2(g)+2H_2O(l)$$
$$ΔH^Θ=−890kJ$$
what is the standard enthalpy change, in kJ, for the following reaction?
$$C(s)+2H_2(g)→CH_4(g)$$

Accepted Answer

-72

Answer

-214

Answer

+72

Answer

+214

Question 25

Consider these equations:
What is the standard enthalpy change, in kJ, for the following reaction?
$$N_2(g)+2H_2(g)→N_2H_4(g)$$

Accepted Answer

Answer

Answer

Answer

Question 26

The standard enthalpy changes for the combustion of carbon and carbon monoxide are shown below.
What is the standard enthalpy change, in kJ, for the following reaction?
$$C(s)+\frac{1}{2}O_2(g)→CO(g)$$

Accepted Answer

-111

Answer

-677

Answer

+111

Answer

+677

Question 27

Consider the equations above. What is the enthalpy change of the reaction below?
$$2CH_4(g)+3\frac{1}{2}O_2(g)→(COOH)_2(s)+3H_2O(l$$

Accepted Answer

2x + 2y + z

Answer

Answer

Answer

2x + 2y + 2z

Question 28

Which statement is correct?

Accepted Answer

In an endothermic reversible reaction, the activation energy of the forward reaction is greater than that of the reverse reaction.

Answer

In an exothermic reaction, the products have more energy than the reactants.

Answer

In an exothermic reversible reaction, the activation energy of the forward reaction is greater than that of the reverse reaction.

Answer

In an endothermic reaction, the products are more stable than the reactants.

Question 29

Which describes the reaction shown in the potential energy profile?

Accepted Answer

The reaction is endothermic and the products have greater enthalpy than the reactants.

Answer

The reaction is endothermic and the reactants have greater enthalpy than the products.

Answer

The reaction is exothermic and the products have greater enthalpy than the reactants.

Answer

The reaction is exothermic and the reactants have greater enthalpy than the products.

Question 30

What can be deduced from this reaction profile?

Accepted Answer

The reactants are less stable than the products and the reaction is exothermic.

Answer

The reactants are less stable than the products and the reaction is endothermic.

Answer

The reactants are more stable than the products and the reaction is exothermic.

Answer

The reactants are more stable than the products and the reaction is endothermic.

Question 31

What can be deduced from the facts that ozone absorbs UV radiation in the region of 340 nm and molecular oxygen in the region of 242 nm?

Accepted Answer

The bonds between atoms in molecular oxygen need more energy to break.

Answer

The bond between atoms in molecular oxygen is a double bond.

Answer

The bonds in ozone are delocalized.

Answer

The bonds between atoms in ozone are stronger than those in molecular oxygen.

Question 32

A student measured the temperature of a reaction mixture over time using a temperature probe. By considering the graph, which of the following deductions can be made?

I. The reaction is exothermic.

II. The products are more stable than the reactants.

III. The reactant bonds are stronger than the product bonds.

Accepted Answer

I and II only

Answer

I and III only

Answer

II and III only

Answer

I, II and III

Question 33

Which statement about bonding is correct?

Accepted Answer

Bond breaking is endothermic and requires energy.

Answer

Bond breaking is endothermic and releases energy.

Answer

Bond making is exothermic and requires energy.

Answer

Bond making is endothermic and releases energy.

Question 34

Which equation best represents the bond enthalpy of HCl?

Accepted Answer

B

Answer

A

Answer

C

Answer

D

Dok Energetics Questions

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