Question 1

Which law is illustrated by the balanced chemical equation $$\mathrm{CH_4$(g) + 2\ O_2$(g) \rightarrow CO_2$(g) + 2\ H_2O(g)} as $$shown in the image, where the number of each type of atom is the same on both sides of the equation?

Accepted Answer

Law of Conservation of Mass

Question 2

Given the reaction $$\mathrm{2\ C_4H_{10}(g) + 13\ O_2$(g) \rightarrow 8\ CO_2$(g) + 10\ H_2O(g)}$$, how many moles of $$\mathrm{CO_2$}$$ are produced from 1 mole of $$\mathrm{C_4H_{10}}$$?

Accepted Answer

$$4$$ moles

Question 3

Which of the following best describes a limiting reactant in a chemical reaction?

Accepted Answer

The reactant that is completely consumed first, limiting the amount of product formed

Question 4

A student mixes $$\mathrm{Pb(NO_3$)_2(aq)}$$ and $$\mathrm{2KI(aq)}$$ and observes a yellow precipitate. What is the net ionic equation for this reaction?

Accepted Answer

$$\mathrm{Pb$$^{2+}$$(aq) + 2I^-(aq) \rightarrow $$PbI_2$$(s)}$$

Question 5

Which of the following compounds is insoluble in water according to the solubility rules?

Accepted Answer

$$\mathrm{AgCl}$$

Question 6

What is the empirical formula of a compound that contains 61.31% C, 5.14% H, 10.21% N, and 23.33% O by mass?

Accepted Answer

$$\mathrm{C_7H_7NO_2}$$

Question 7

Which of the following is a redox reaction?

Accepted Answer

$$\mathrm{Zn(s) + 2H^+(aq) \rightarrow Zn$$^{2+}$$(aq) + H_2$(g)}$$

Question 8

What is the oxidation number of sulfur in $$\mathrm{H_2SO_4}$$?

Accepted Answer

$$+6$$

Question 9

A solution is prepared by dissolving 5.25 g of oxalic acid ($$\mathrm{C_2O_4H_2}) in 155 mL of $$water. What is the percent by mass of oxalic acid in the solution? (Assume the density of water is $$1.00\ \mathrm{g/mL}.)$$

Accepted Answer

$$3.28\%$$

Question 10

Which of the following is the correct balanced equation for the combustion of ethane ($$\mathrm{C_2H_6}$$)?

Accepted Answer

$$\mathrm{2C_2H_6 + 7O_2 \rightarrow 4CO_2 + 6H_2O}$$

Question 11

If 28.6 kg of C reacts with 88.2 kg of $$\mathrm{$$TiO_2$$} to $$produce 42.8 kg of Ti, what is the percent yield of Ti? (Molar masses: C = 12.01 g/mol, $$\mathrm{$$TiO_2$$} = 79.87 g/$$mol, Ti = 47.87 g/mol)

Accepted Answer

$$80.9\%$$

Question 12

Which of the following is a strong acid?

Accepted Answer

$$\mathrm{$$HNO_3$$}$$

Question 13

How many molecules are present in 0.032 g of $$\mathrm{H_2O}$$? (Molar mass of $$\mathrm{H_2O} = 18.02 g/$$mol, Avogadro's number $$= 6.022 	imes 10$$^{23}$$)

Accepted Answer

$$1.07 	imes 10$$^{21}$$

Question 14

Which of the following is the net ionic equation for the neutralization of HCl with NaOH?

Accepted Answer

$$\mathrm{H^+(aq) + OH^-(aq) \rightarrow H_2O(l)}$$

Question 15

A 1.0 M solution of $$\mathrm{$$CaCl_2$$}$$ contains how many moles of $$\mathrm{Cl^-}$$ ions per liter?

Accepted Answer

$$2.0$$ mol

Question 16

Which of the following is the correct molecular formula for a compound with an empirical formula of $$\mathrm{CH_2O}$$ and a molar mass of 180 g/mol?

Accepted Answer

$$\mathrm{C_6H_{12}O_6$}$$

Question 17

Which of the following best describes a precipitation reaction?

Accepted Answer

A reaction in which an insoluble solid forms when two solutions are mixed

Question 18

What is the theoretical yield of Ti (in kg) when 88.2 kg of $$\mathrm{$$TiO_2$$}$$ reacts with excess C? (Molar mass $$\mathrm{$$TiO_2$$} = 79.87 g/$$mol, Ti = 47.87 g/mol, $$\mathrm{$$TiO_2$$(s) + 2C(s) \rightarrow Ti(s) + 2CO(g)})$$

Accepted Answer

$$52.9 kg$$

Stoichiometry and Chemical Reactions: Balancing, Types, and Calculations

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