Question 1

Which of the following best describes the Law of Conservation of Mass as it applies to chemical equations?

Accepted Answer

The total mass of reactants must equal the total mass of products.

Question 2

Why is it incorrect to balance chemical equations by changing the subscripts in chemical formulas?

Accepted Answer

Changing subscripts alters the chemical compound, resulting in a different substance.

Question 3

Given the unbalanced equation $$\mathrm{CH_4$ + O_2$ \rightarrow CO_2$ + H_2O}$$, what are the correct coefficients to balance the equation?

Accepted Answer

$$1, 2, 1, 2$$

Question 4

Which symbol in a chemical equation indicates that a substance is dissolved in water?

Accepted Answer

$$(aq)$$

Question 5

What is the product of the combination reaction between sodium metal and chlorine gas?

Accepted Answer

$$\mathrm{NaCl}$$

Question 6

Which of the following is a decomposition reaction?

Accepted Answer

$$\mathrm{$$CaCO_3$$ \rightarrow CaO + CO_2$}$$

Question 7

A combustion reaction of propane ($$\mathrm{C_3H_8}) in $$oxygen produces which products?

Accepted Answer

$$\mathrm{CO_2$}$$ \, and \, \mathrm{H_2O}$

Question 8

In the reaction $$\mathrm{4Fe(s) + 3O_2(g) \rightarrow 2Fe_2O_3(s)}$$, how many moles of $$\mathrm{Fe_2O_3}$$ are produced from 31.2 mol of Fe?

Accepted Answer

$$15.6$$ \, moles

Question 9

A plant consumes 37.8 g of $$\mathrm{CO_2$} in a $$week. Using the photosynthesis reaction $$\mathrm{6CO_2 + 6H_2O \rightarrow C_6H_{12}O_6$ + 6O_2}$$, what mass of glucose ($$\mathrm{C_6H_{12}O_6$}) $$can be synthesized? (Molar masses: $$\mathrm{CO_2$} = 44.0 g/$$mol, $$\mathrm{C_6H_{12}O_6$} = 180.0 g/$$mol)

Accepted Answer

$$25.8$$ \, g

Question 10

In a reaction mixture containing 42.5 g Mg and 33.8 g O$$_2$$, what is the limiting reactant for the reaction $$\mathrm{2Mg + O_2$ \rightarrow 2MgO}$$? (Molar masses: Mg = 24.3 g/mol, O$$_2 = 32.0 g/$$mol)

Accepted Answer

Oxygen

Question 11

What is the percent yield if 42.8 kg of Ti is produced from the reaction $$\mathrm{$$TiO_2$$(s) + 2C(s) \rightarrow Ti(s) + 2CO(g)}$$ using 88.2 kg of TiO$$_2$$ and 22.4 kg of C? (Molar masses: TiO$$_2 = 79.9 g/$$mol, Ti = 47.9 g/mol)

Accepted Answer

$$54.1\%$$

Question 12

Which of the following best describes a combination reaction?

Accepted Answer

Two or more reactants combine to form a single product.

Question 13

Which of the following is true about the coefficients in a balanced chemical equation?

Accepted Answer

They indicate the relative number of moles of reactants and products.

Question 14

In the reaction $$\mathrm{2H_2(g) + O_2$(g) \rightarrow 2H_2O(g)}$$, if you start with 5 moles of $$\mathrm{H_2$}$$ and 2 moles of $$\mathrm{O_2$}$$, what is the limiting reactant?

Accepted Answer

$$\mathrm{O_2$}$$

Question 15

Which of the following is the correct formula for the product formed when potassium reacts with water?

Accepted Answer

$$\mathrm{KOH}$$

Question 16

Which of the following reactions is a combustion reaction?

Accepted Answer

$$\mathrm{CH_4$ + 2O_2 \rightarrow CO_2$ + 2H_2O}$$

Question 17

If 1.00 g of $$\mathrm{C_6H_{12}O_6$} is $$combusted according to $$\mathrm{C_6H_{12}O_6$ + 6O_2 \rightarrow 6CO_2 + 6H_2O}$$, how many grams of water are produced? (Molar mass $$\mathrm{C_6H_{12}O_6$} = 180.0 g/$$mol, $$\mathrm{H_2O} = 18.0 g/$$mol)

Accepted Answer

$$0.60$$ \, g

Question 18

What is the theoretical yield of $$\mathrm{MgO}$$ when 42.5 g of Mg reacts with excess $$\mathrm{O_2$}$$? (Molar mass Mg = 24.3 g/mol, MgO = 40.3 g/mol, $$\mathrm{2Mg + O_2$ \rightarrow 2MgO})$$

Accepted Answer

$$70.5$$ \, g

Chemical Reactions and Reaction Stoichiometry: Study Notes

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