Q: What is the value of $$K$$ for the reaction $$A + B \rightleftharpoons C if$$ $$[A] = 0.2 M$$, $$[B] = 0.3 M$$, and $$[C] = 0.6 M$$?

$$K = \dfrac{[C]}{[A][B]} = \dfrac{0.6}{0.2 \times 0.3} = 10$$

Question 1

Which of the following reactions is a decomposition reaction?

Accepted Answer

$$2H_2O \rightarrow 2H_2 + O_2$

Question 2

In the reaction $$2Na + Cl_2$ \rightarrow 2NaCl$$, which element is oxidized?

Accepted Answer

Sodium ($$Na)$$

Question 3

What is the oxidation state of sulfur in $$SO_2$$?

Accepted Answer

$$+4$$

Question 4

How many molecules are in 0.5 moles of $$CO_2$$? (Avogadro’s number $$= 6.02 	imes 10$$^{23}$$)

Accepted Answer

$$3.01 	imes 10$$^{23}$$

Question 5

A reaction has a theoretical yield of 10 g, but only 7 g of product is obtained. What is the percent yield?

Accepted Answer

$$70\%$$

Question 6

Which of the following best describes an exothermic reaction?

Accepted Answer

A reaction that releases heat and has a negative $$\Delta H$$

Question 7

Which of the following is the limiting reactant when 5 g of $$H_2$$ reacts with 20 g of $$O_2 to $$form water? ($$2H_2 + O_2$ \rightarrow 2H_2O$$; molar masses: $$H_2 = 2$ g/mol, O_2$ = 32 g/$$mol)

Accepted Answer

$$H_2$$

Question 8

Which of the following factors will increase the rate of a chemical reaction?

Accepted Answer

Adding a catalyst

Question 9

According to LeChatelier’s principle, what happens to the equilibrium position if more reactant is added to a system at equilibrium?

Accepted Answer

The equilibrium shifts toward the products

Question 10

What is the value of $$K$$ for the reaction $$A + B \rightleftharpoons C if$$ $$[A] = 0.2 M$$, $$[B] = 0.3 M$$, and $$[C] = 0.6 M$$?

Accepted Answer

$$K = \dfrac{[C]}{[A][B]} = \dfrac{0.6}{0.2 	imes 0.3} = 10$$

Question 11

Which gas law explains why a balloon shrinks when placed in a freezer?

Accepted Answer

Charles’ Law

Question 12

At STP, what is the volume occupied by 3 moles of an ideal gas?

Accepted Answer

$$67.2 L$$

Question 13

A mixture contains $$P_{O_2$} = 200$$ mmHg, $$P_{N_2$} = 500$$ mmHg, and $$P_{CO_2$} = 300$$ mmHg. What is the total pressure?

Accepted Answer

$$1000$$ mmHg

Question 14

Which of the following molecules would have the highest boiling point due to strong intermolecular forces?

Accepted Answer

$$H_2O$$

Question 15

Which phase change is exothermic?

Accepted Answer

Condensation

Question 16

A patient receives a cold pack for an injury. Which type of reaction occurs in the cold pack?

Accepted Answer

Endothermic reaction

Question 17

Which of the following statements about ATP is correct?

Accepted Answer

ATP releases energy when a phosphate group is removed

Question 18

If the pressure of a gas is doubled while the temperature and amount remain constant, what happens to the volume according to Boyle’s Law?

Accepted Answer

Volume halves

Question 19

Which of the following is NOT a greenhouse gas?

Accepted Answer

$$N_2$$

Question 20

A sample of gas has a volume of 10 L at 300 K. What will its volume be at 600 K if pressure and amount are constant?

Accepted Answer

$$20 L$$

Chem 101 Exam 3 Study Guide: Chemical Reactions, Energy, Gases, and Phase Changes

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