Question 1

A patient is given 0.350 moles of sodium (Na) as part of a treatment. How many grams of sodium does this correspond to? (Molar mass of Na = 22.99 g/mol)

Accepted Answer

$$8.05 g$$

Question 2

Calculate the mass of $$3.00$$ moles of $$\mathrm{CF_2Cl_2} (C = 12.01 g/$$mol, F = 19.00 g/mol, Cl = 35.45 g/mol).

Accepted Answer

$$363 g$$

Question 3

In the balanced reaction $$\mathrm{Fe_2S_3 + 4\ O_2$ \rightarrow 2\ FeO + 3\ SO_2$}$$, what is the mole ratio of $$\mathrm{Fe_2S_3} to$$ $$\mathrm{O_2$}$$?

Accepted Answer

1 to 4

Question 4

How many moles are present in $$8.65$$ grams of $$\mathrm{NaCl}$$? (Molar mass of $$\mathrm{NaCl}$$ = $$58.44 g/$$mol)

Accepted Answer

$$0.148$$ mol

Question 5

The mass of $$1.21 	imes 10$$^{20}$$ atoms of sulfur is:

Accepted Answer

$$6.44 mg$$

Question 6

What is the molar mass of $$\mathrm{Co(NO_3$)_2}$$?

Accepted Answer

$$182.94 g/$$mol

Question 7

Determine the number of moles of aluminum in $$96.7 g of Al. ($$Molar mass of Al = $$26.98 g/$$mol)

Accepted Answer

$$3.58$$ mol

Question 8

How many molecules are present in $$4.25$$ mol of $$\mathrm{$$CCl_4$$}$$? (Avogadro's number $$= 6.02 	imes 10$$^{23}$$)

Accepted Answer

$$2.56 	imes 10$$^{24}$$

Question 9

Given the balanced chemical reaction: $$\mathrm{$$CaCl_2$$(aq) + K_2CO_3(aq) \rightarrow 2\ KCl(aq) + $$CaCO_3$$(s)}$$, how many grams of calcium chloride (molar mass $$= 111.0 g/$$mol) are needed to produce $$10.0 g of $$potassium chloride (molar mass $$= 74.55 g/$$mol)?

Accepted Answer

$$7.44 g$$

Question 10

Calculate the molecular mass of menthol, $$\mathrm{C$$_{10}$$H_{20}O$$}$.

Accepted Answer

$$156$$ amu

Question 11

Which of the following best describes activation energy?

Accepted Answer

The minimum amount of energy required for reactants to collide and react.

Question 12

Consider the following reaction at equilibrium: $$2\mathrm{NO_2$}(g) \rightleftharpoons 2\mathrm{NO}(g) + \mathrm{O_2$}(g). In $$which direction will the reaction shift if $$\mathrm{NO} is $$removed from the system?

Accepted Answer

The reaction will shift toward the left to produce more $$\mathrm{NO_2$}.$$

Question 13

For the reaction $$2\mathrm{NOBr}(g) \rightleftharpoons 2\mathrm{NO}(g) + \mathrm{Br_2$}(g)$$, which of the following changes would cause the $$\mathrm{Br_2$}$$ concentration to increase?

Accepted Answer

Remove some $$\mathrm{NO}.$$

Question 14

When a reaction system is at equilibrium:

Accepted Answer

The rates of the forward and reverse reactions are exactly equal.

Question 15

The function of a catalyst in a reaction system is to:

Accepted Answer

Lower the activation energy.

Question 16

A reaction that is spontaneous can be described as:

Accepted Answer

Proceeding without external influence once it has begun.

Question 17

Which of the following statements is true about chemical equilibrium in general?

Accepted Answer

At equilibrium, the rate of the forward reaction is equal to the rate of the reverse reaction.

Question 18

Which of the following changes would increase the rate of a reaction?

Accepted Answer

Increasing temperature

Question 19

When a reaction is spontaneous, the sign of $$\Delta G is$$:

Accepted Answer

Negative

Question 20

Which of these situations will result if some $$\mathrm{CH_4$}(g) is $$removed from the reaction $$\mathrm{CO(g) + 3H_2(g) \rightleftharpoons CH_4$(g) + H_2O(g)} at $$equilibrium?

Accepted Answer

More $$\mathrm{CH_4$}$$ and $$\mathrm{H_2O}$$ will be produced.

GOB Chemistry Study Notes: Moles, Stoichiometry, Chemical Equilibrium, and Reaction Energetics

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