Q: Which equation correctly expresses percent yield?

$$\text{Percent yield} = \frac{\text{actual yield}}{\text{theoretical yield}} \times 100\%$$

Q: Which of the following statements about molarity is correct?

Molarity ($$M) is $$defined as $$\frac{\text{moles of solute}}{\text{liters of solution}}.$$

Question 1

Which of the following best describes the greenhouse effect and its connection to atmospheric CO$$_2$$ levels?

Accepted Answer

Greenhouse gases allow sunlight to enter the atmosphere, warm Earth's surface, and prevent some heat from escaping, leading to increased global temperatures as CO$$_2$$ levels rise.

Question 2

Given the balanced equation for octane combustion: $$2\ \mathrm{C}_8\mathrm{H}_{18}(l) + 25\ \mathrm{O}_2(g) \rightarrow 16\ \mathrm{CO}_2(g) + 18\ \mathrm{H}_2\mathrm{O}(g)$$, how many moles of CO$$_2$$ are produced from burning $$44.0$$ moles of octane?

Accepted Answer

$$352$$ moles

Question 3

If $$3.7 	imes 10$$^{15}$$ g of octane ($$\mathrm{C}_8\mathrm{H}_{18}$$, molar mass 114.22$ g/mol) is burned, how many grams of CO_2$ (44.01$ g/mol) are produced? Use the equation: 2$$\ \mathrm{C}_8\mathrm{H}_{18}(l) + 25\ \mathrm{O}_2(g) ightarrow 16\ \mathrm{CO}_2(g) + 18\ \mathrm{H}_2\mathrm{O}(g)$$.

Accepted Answer

$$1.1 	imes 10$$^{16}$$ g

Question 4

A pizza recipe requires $$1$$ crust, $$5 oz $$tomato sauce, and $$2$$ cups cheese per pizza. If you have $$4$$ crusts, $$10$$ cups cheese, and $$15 oz $$tomato sauce, what is the limiting reactant and how many pizzas can you make?

Accepted Answer

Tomato sauce is limiting; $$3$$ pizzas can be made.

Question 5

Which of the following best defines the theoretical yield in a chemical reaction?

Accepted Answer

The amount of product that can be made based on the amount of limiting reactant.

Question 6

A reaction mixture contains $$42.5 g Mg $$and $$33.8 g O$_2. $$Using $$2\ \mathrm{Mg}(s) + \mathrm{O}_2(g) \rightarrow 2\ \mathrm{MgO}(s)$$, which is the limiting reactant and what is the theoretical yield of MgO (molar mass $$40.31 g/$$mol)?

Accepted Answer

Mg is limiting; $$70.9 g $$MgO is the theoretical yield.

Question 7

Which equation correctly expresses percent yield?

Accepted Answer

$$	ext{Percent yield} = \frac{	ext{actual yield}}{	ext{theoretical yield}} 	imes 100\%$$

Question 8

Which of the following statements about molarity is correct?

Accepted Answer

Molarity ($$M) is $$defined as $$\frac{	ext{moles of solute}}{	ext{liters of solution}}.$$

Question 9

How many liters of $$0.500 M $$NaCl solution contain $$1.00$$ mol NaCl?

Accepted Answer

$$2.00 L$$

Question 10

Which equation is used to calculate the volume of a diluted solution prepared from a stock solution?

Accepted Answer

$$M_1$$ $$V_1$$ = $$M_2$$ $$V_2$$

Question 11

Which of the following best describes a strong electrolyte?

Accepted Answer

A substance that completely dissociates into ions in water and conducts electricity well.

Question 12

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

Accepted Answer

AgCl

Question 13

What is the net ionic equation for the reaction between Na$$_2CO$_3(aq) $$and HCl(aq)?

Accepted Answer

$$\mathrm{CO}_3$$^{2-}$$(aq) + 2\ \mathrm{H}^+(aq) \rightarrow \mathrm{CO}_2(g) + \mathrm{H}_2\mathrm{O}(l)$$

Question 14

Which of the following is the correct net ionic equation for the neutralization of HCl(aq) with NaOH(aq)?

Accepted Answer

$$\mathrm{H}^+(aq) + \mathrm{OH}^-(aq) \rightarrow \mathrm{H}_2\mathrm{O}(l)$$

Question 15

Which of the following reactions is a redox reaction?

Accepted Answer

$$2\ \mathrm{Na}(s) + \mathrm{Cl}_2(g) \rightarrow 2\ \mathrm{NaCl}(s)$$

Question 16

Assign the oxidation states to all elements in CO$$_2.$$

Accepted Answer

C: $$+4$$, O: $$-2$$

Question 17

Which of the following best describes the role of the reducing agent in a redox reaction?

Accepted Answer

It donates electrons and is oxidized.

Question 18

Which of the following is a characteristic of a combustion reaction?

Accepted Answer

A substance reacts with O$$_2 to $$form one or more oxygen-containing compounds and emits heat.

Chemical Quantities and Aqueous Reactions: Stoichiometry, Solutions, and Reaction Types

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