Q: What is the percent yield if the theoretical yield of titanium is 52.9 kg, but only 42.8 kg is actually produced in the reaction $$\mathrm{$$TiO_2$$}(s) + 2\mathrm{C}(s) \rightarrow \mathrm{Ti}(s) + 2\mathrm{CO}(g)$$?

$$\frac{42.8}{52.9} \times 100\% = 80.9\%$$

Question 1

Which of the following best describes the role of greenhouse gases in Earth's atmosphere, as illustrated in the first image?

Accepted Answer

They allow visible light to pass through and trap some of the heat radiated from Earth's surface.

Question 2

Based on the second image, which shows temperature deviation over time, what trend is observed in global temperatures since 1880?

Accepted Answer

There has been a significant increase in global temperatures, especially after 1980.

Question 3

The third image shows atmospheric carbon dioxide concentration over time. What relationship can be inferred between atmospheric CO2 and global temperature from the provided images?

Accepted Answer

As atmospheric CO2 concentration increases, global temperature also increases.

Question 4

Which of the following chemical equations is correctly balanced for the combustion of butane ($$\mathrm{C_4H_{10}}$$)?

Accepted Answer

$$2\mathrm{C_4H_{10}}(g) + 13\mathrm{O_2$}(g) \rightarrow 8\mathrm{CO_2$}(g) + 10\mathrm{H_2O}(g)$$

Question 5

A plant consumes 37.8 g of $$\mathrm{CO_2$} in $$one week. Using the equation $$6\mathrm{CO_2$}(g) + 6\mathrm{H_2O}(l) \xrightarrow{sunlight} C_6H_{12}O_6$(aq) + 6O_2(g)$$, what mass of glucose ($$\mathrm{C_6H_{12}O_6$}) $$can be synthesized? (Molar masses: $$\mathrm{CO_2$} = 44.01 g/$$mol, $$\mathrm{C_6H_{12}O_6$} = 180.16 g/$$mol)

Accepted Answer

25.9 g

Question 6

Which of the following statements about balancing chemical equations is correct?

Accepted Answer

Coefficients are changed to balance the number of atoms; subscripts should not be changed.

Question 7

In the reaction $$2\mathrm{NO}(g) + 5\mathrm{H_2$}(g) \rightarrow 2\mathrm{NH_3$}(g) + 2\mathrm{H_2O}(g)$$, if you start with 86.3 g of NO and 25.6 g of H2, what is the theoretical yield of ammonia ($$\mathrm{NH_3$}) in $$grams? (Molar masses: NO = 30.01 g/mol, H2 = 2.02 g/mol, NH3 = 17.03 g/mol)

Accepted Answer

49.0 g

Question 8

Which reactant is limiting when 2 mol of nitrogen gas reacts with 8 mol of hydrogen gas to form ammonia according to $$N_2(g) + 3H_2(g$$) \rightarrow 2NH_3(g)$$?

Accepted Answer

Hydrogen gas

Question 9

What is the percent yield if the theoretical yield of titanium is 52.9 kg, but only 42.8 kg is actually produced in the reaction $$\mathrm{$$TiO_2$$}(s) + 2\mathrm{C}(s) \rightarrow \mathrm{Ti}(s) + 2\mathrm{CO}(g)$$?

Accepted Answer

$$\frac{42.8}{52.9} 	imes 100\% = 80.9\%$$

Question 10

Which of the following is the correct balanced equation for the reaction between potassium metal and bromine gas?

Accepted Answer

$$2K(s) + Br_2$(g) \rightarrow 2KBr(s)$$

Question 11

A dose of 3.26 g of $$\mathrm{Mg(OH)_2}$$ neutralizes HCl according to $$\mathrm{Mg(OH)_2}(aq) + 2\mathrm{HCl}(aq) \rightarrow 2\mathrm{H_2O}(l) + \mathrm{$$MgCl_2$$}(aq). $$What mass of HCl is neutralized? (Molar masses: $$\mathrm{Mg(OH)_2} = 58.32 g/$$mol, HCl = 36.46 g/mol)

Accepted Answer

4.07 g

Question 12

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

Accepted Answer

The reactant that produces the least amount of product and is completely consumed.

Question 13

Which of the following is the correct balanced equation for the combustion of liquid methyl alcohol ($$\mathrm{CH_3OH}$$)?

Accepted Answer

$$2\mathrm{CH_3OH}(l) + 3\mathrm{O_2$}(g) \rightarrow 2\mathrm{CO_2$}(g) + 4\mathrm{H_2O}(g)$$

Question 14

If 5 mol of $$\mathrm{NO_2$}$$ and 1 mol of $$\mathrm{H_2O}$$ react completely according to $$3\mathrm{NO_2$}(g) + \mathrm{H_2O}(l) \rightarrow 2\mathrm{$$HNO_3$$}(l) + \mathrm{NO}(g)$$, how many moles of the reactant in excess remain after the reaction?

Accepted Answer

3 mol $$\mathrm{NO_2$}$$

Question 15

Which of the following best explains why changing the subscript in a chemical formula when balancing an equation is incorrect?

Accepted Answer

Changing the subscript changes the identity of the compound.

Question 16

Which of the following is a correct balanced equation for the reaction between solid silicon dioxide and solid carbon to produce solid silicon carbide and carbon monoxide gas?

Accepted Answer

$$\mathrm{$$SiO_2$$}(s) + 3\mathrm{C}(s) \rightarrow \mathrm{SiC}(s) + 2\mathrm{CO}(g)$$

Question 17

In a reaction, 1 mol of A reacts with 3 mol of B. If a flask contains 12 mol of B, how many mol of A are required to completely react with B?

Accepted Answer

4 mol

Question 18

Which of the following best describes the trend in the reactivity of alkali metals with halogens, as shown in the fourth image?

Accepted Answer

Successive alkali metals react more vigorously with halogens.

Chemical Reactions and Chemical Quantities: Chapter 4 Study Guide

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