1- Use the reaction to complete the sentence.

2CO + O2 → 2CO2

Carbon monoxide and oxygen combine to produce carbon dioxide. The total bond energy of the products is 1,472 kJ. The bond energy of each carbon-oxygen bond in carbon dioxide is _____.

(1 point)

a 368 kJ

b 1,472 kJ

c 736 kJ

d 2,944 kJ

2-Use the table to answer the question.

Reaction CH4 + 4Cl2 → CCl4 + 4HCl
Reactants Products
Bonds Present
4 H–C

4 Cl–Cl

4 C–Cl

4 H–Cl

Energy of Bonds Broken (Reactants) / Formed (Products)

4 × 411 kJ/mol

4 × 242 kJ/mol

4 × 327 kJ/mol

4 × 427 kJ/mol

Which statement about the change in bond energy of this reaction is correct?

(1 point)

a The reaction is exothermic because the total bond energy of the reactants is less than the total bond energy of the products.

b The reaction is exothermic because the energy of each bond in the reactants is greater than the energy of a bond in the products.

c The reaction is endothermic because the energy of each bond in the reactants is less than the energy of a bond in the products.

d The reaction is endothermic because the total bond energy of the reactants is greater than the total bond energy of the products.

3-A chemist is performing a chemical reaction under a fume hood. The chemist has a set of beakers, flasks, and tubes set up under the fume hood, with various liquids being combined inside the glass containers. The fume hood is turned on in order to withdraw any toxic gases and expel them outside the building.

Which part of this system is designated as the chemical reaction system?

(1 point)

a the glass containers

b inside the fume hood

c liquid contents of the glass containers

d outside of the building

4-In order to break water into hydrogen and oxygen, water is heated to more than 500°C. Which kind of reaction is this and why?(1 point)

a It is endothermic because heat needs to be absorbed by the reactants to form the products.

b It is exothermic because heat needs to be absorbed by the reactants to form the products.

c It is endothermic because heat needs to be released by the reactants to form the products.

d It is exothermic because heat needs to be released by the reactants to form the products.

5-On an energy graph, the length of vertical lines represents _____.(1 point)

a the amount of released or absorbed energy

b the number of atoms in the activated complex

c whether energy is released or absorbed

d the number of reactant and product atoms

6-The dissolution of ammonium nitrate in water is given by the following equation:

NH4NO3(s) + heat → NH4+(aq) + NO3-(aq)

Which statement best describes what an energy graph of this reaction would look like?

(1 point)

a The reactants would appear at a lower energy state than the products.

b The reactants would appear at a higher energy state than the products.

c The reactants and products would appear at a low energy state.

d The reactants and products would appear at a high energy state.

7-In the reaction of hydrogen gas and oxygen gas to form water, the glowing splint(1 point)

a is one of the reactants of the reaction.

b provides the kinetic energy for the reaction

c is one of the products of the reaction.

d provides the activation energy for the reaction.

8- Use the diagram to answer the question.

A diagram shows the energy levels of hydrogen chloride and molecules of hydrogen and chlorine.

The diagram represents the electrolysis of hydrochloric acid (HCl) to form hydrogen gas (H2) and chlorine gas (Cl2). Which statement best describes the reaction?

(1 point)

a The formation of the products releases activation energy, and this energy is less than the energy that is absorbed by the reactants.

b The formation of the products releases activation energy, and this energy is greater than the energy that is absorbed by the reactants.

c The formation of the products releases bond energy, and this energy is less than the energy that is absorbed by the reactants.

d The formation of the products releases bond energy, and this energy is greater than the energy that is absorbed by the reactants.

9- Use the reaction to answer the question.

C2H4 + O2 → CO2 + H2O

How many bonds are broken when performing the reaction? How many bonds are formed?

(1 point)

a Four C–H, one C=C, and three O=O bonds need to break up. Four C=O and four O–H bonds need to form.

b Four C–H, one C=C, and one O=O bond need to break up. Two C=O and two O–H bonds need to form.

c Four C–H, one C–C, and three O–O bonds need to break up. Four C–O and four O–H bonds need to form.

d Four C–H, one C–C, and one O–O bond need to break up. Two C–O and two O–H bonds need to form.

10-Which phrase defines bond energy?(1 point)

a energy input needed to break reactant bonds

b energy stored in chemical bonds

c energy output when product bonds form

d energy required to break a chemical bond

11- Catalysts speed up chemical reactions. Which change is a likely direct effect of a catalyst?(1 point)

a increasing chemical potential energy

b increasing activation energy

c decreasing chemical potential energy

d decreasing activation energy

12- Is the process of water evaporating endothermic or exothermic?(1 point)

a It is exothermic because heat from the surroundings has to be absorbed by the water in order to change states.

b It is endothermic because heat from the surroundings has to be absorbed by the water in order to change states.

c It is exothermic because as the liquid water changes into water vapor, it releases heat into the air.

d It is endothermic because as the liquid water changes into water vapor, it releases heat into the air.

13- A burner in a gas stove breaks propane and oxygen up to form carbon dioxide and water, thereby heating a home. Which part is the source of the activation energy required, and is this reaction endothermic or exothermic?(1 point)

a The flame from the burner provides the energy to perform the reaction. The reaction is endothermic.

b The burning propane gas provides the energy to perform the reaction. The reaction is exothermic.

c The burning propane gas provides the energy to perform the reaction. The reaction is endothermic.

d The flame from the burner provides the energy to perform the reaction. The reaction is exothermic.

14- Which change does heat energy cause?(1 point)

a more collisions between molecules

b slower molecule movement

c greater energy differences between molecules

d reduced energy transfer

15- Which statement is true about molecule speed?(1 point)

a Faster molecules have more energy than slower molecules.

b Faster molecules have fewer collisions than slower molecules.

c Slower molecules are smaller than faster molecules.

d Slower molecules are oriented better than faster molecules.

16- The chemical reaction shown is exothermic.

CH4 + N2 + H2 → CH3N + NH3

Which statement about the reaction is correct?

(1 point)

a It takes more energy to form C–H bonds in the reactants than is released from C–H bonds in the products.

b The total chemical potential energy of the reactants is greater than the total chemical potential energy of the products.

c More chemical potential energy is stored in the bonds of CH4 than in the bonds of CH3N.

d Each reactant has more chemical potential energy than each product.

17- A scientist wants to perform a reaction in a vacuum chamber to control the experiment as much as possible and to prevent other variables from impacting the reaction. The scientist is trying to determine if the reaction is endothermic or exothermic and measure how much energy is absorbed or given off. Is this a sound approach? Why or why not? In three to five sentences, explain your reasoning.(4 points)

18- A chemist wants to observe the following reaction:

2H2 + O2 → 2H2O

The chemist is standing inside a room with oxygen in the air and has a balloon filled with hydrogen. The chemist holds a small flame up to the hydrogen balloon. When the balloon pops, the hydrogen explodes in a ball of fire.

Based on what you know about breaking and forming bonds, explain which part of the reaction is higher in energy (i.e., does it take more energy to break the bonds of the reactants, or is more energy given off when the product bonds are formed?). Defend your answer in three to five sentences.

(4 points)

19- A scientist studies the bond energies of different compounds containing nitrogen (N). The scientist observes that the N–N bonds in one group of compounds have a bond energy of 209 kJ/mol, while the N–N bonds in another group of compounds have a bond energy of 418 kJ/mol. In one or two sentences, postulate a reason for this difference.(2 points)

1-736 kJ

2-The reaction is exothermic because the total bond energy of the reactants is less than the total bond energy of the products.
3-liquid contents of the glass containers
4-It is endothermic because heat needs to be absorbed by the reactants to form the products.
5-the amount of released or absorbed energy
6-The reactants would appear at a lower energy state than the products.
7-provides the activation energy for the reaction.
8-The formation of the products releases bond energy, and this energy is less than the energy that is absorbed by the reactants.
9-Four C–H, one C=C, and three O=O bonds need to break up. Four C=O and four O–H bonds need to form.
10-energy required to break a chemical bond
11-decreasing activation energy
12-It is endothermic because heat from the surroundings has to be absorbed by the water in order to change states.
13-The flame from the burner provides the energy to perform the reaction. The reaction is exothermic.
14-more collisions between molecules
15-Faster molecules have more energy than slower molecules.
16-The total chemical potential energy of the reactants is greater than the total chemical potential energy of the products.

gaia is right btw ^^

titan^ mans if it's wrong for you then you took a dif test i got 100.

Gaia is 100% correct, I didn't trust him though and used the people on brainly and got a failing grade. Please don't make the same mistake I did because the only questions I got wrong were ones from brainly. Gaia is fully correct

I might be wrong but for;

18.(paraphrasing) It’d be exothermic, with more energy needed to form the bonds in the products. When the hydrogen comes in contact with oxygen after the balloon is popped an exothermic reaction occurs and heat energy is released.

its E3 CHEM B:R - Energy in Chemical Reactions II Unit Test

Gaia is 100% correct for Energy in Chemical Reactions II Unit Test

Just took it <3

Good refresher to see the very first answer in response to the question is all of the answers that are correct and isnt a post hopper that goes ImAgInE ChEaTiNg

Remember guys, it’s not cheating unless u got caught

anyone got a (sort of) answer for question 19 im at a complete loss tbh