Chapter 4

You have \(250 .\) mL of \(0.136 \mathrm{M}\) HCl. Using a volumetric pipet, you take \(25.00 \mathrm{mL}\) of that solution and dilute it to \(100.00 \mathrm{mL}\) in a volumetric flask. Now you take \(10.00 \mathrm{mL}\) of that solution, using a volumetric pipet, and dilute it to \(100.00 \mathrm{mL}\) in a volumetric flask. What is the concentration of hydrochloric acid in the final solution?

Suppose you have \(100.00 \mathrm{mL}\) of a solution of a dye and transfer \(2.00 \mathrm{mL}\) of the solution to a 100.00 -mL volumetric flask. After adding water to the \(100.00 \mathrm{mL}\) mark, you take \(5.00 \mathrm{mL}\) of that solution and again dilute to 100.00 mL. If you find the dye concentration in the final diluted sample is \(0.000158 \mathrm{M},\) what was the dye concentration in the original solution?

A table wine has a pH of 3.40. What is the hydronium ion concentration of the wine? Is it acidic or basic?

A saturated solution of milk of magnesia, \(\mathrm{Mg}(\mathrm{OH})_{2},\) has a pH of \(10.5 .\) What is the hydronium ion concentration of the solution? Is the solution acidic or basic?

What is the hydronium ion concentration of a \(0.0013 \mathrm{M}\) solution of \(\mathrm{HNO}_{3} ?\) What is its \(\mathrm{pH} ?\)

What is the hydronium ion concentration of a \(1.2 \times 10^{-4} \mathrm{M}\) solution of \(\mathrm{HClO}_{4} ?\) What is its \(\mathrm{pH} ?\)

What volume of \(0.109 \mathrm{M} \mathrm{HNO}_{3},\) in milliliters, is required to react completely with \(2.50 \mathrm{g}\) of \(\mathrm{Ba}(\mathrm{OH})_{2} ?\) $$2 \mathrm{HNO}_{3}(\mathrm{aq})+\mathrm{Ba}(\mathrm{OH})_{2}(\mathrm{s}) \rightarrow 2 \mathrm{H}_{2} \mathrm{O}(\ell)+\mathrm{Ba}\left(\mathrm{NO}_{3}\right)_{2}(\mathrm{aq})$$

What mass of \(\mathrm{Na}_{2} \mathrm{CO}_{3},\) in grams, is required for complete reaction with \(50.0 \mathrm{mL}\) of \(0.125 \mathrm{M}\) \(\mathrm{HNO}_{3} ?\) $$\mathrm{Na}_{2} \mathrm{CO}_{3}(\mathrm{aq})+2 \mathrm{HNO}_{3}(\mathrm{aq}) \rightarrow 2 \mathrm{NaNO}_{3}(\mathrm{aq})+\mathrm{CO}_{2}(\mathrm{g})+\mathrm{H}_{2} \mathrm{O}(\ell)$$

When an electric current is passed through an aqueous solution of \(\mathrm{NaCl}\), the valuable industrial chemicals \(\mathrm{H}_{2}(\mathrm{g}), \mathrm{Cl}_{2}(\mathrm{g}),\) and \(\mathrm{NaOH}\) are produced. $$2 \mathrm{NaCl}(\mathrm{aq})+2 \mathrm{H}_{2} \mathrm{O}(\ell) \rightarrow \mathrm{H}_{2}(\mathrm{g})+\mathrm{Cl}_{2}(\mathrm{g})+2 \mathrm{NaOH}(\mathrm{aq})$$ What mass of NaOH can be formed from 15.0 L of 0.35 M NaCl? What mass of chlorine is obtained?

Hydrazine, \(\mathrm{N}_{2} \mathrm{H}_{4},\) a base like ammonia, can react with sulfuric acid. $$2 \mathrm{N}_{2} \mathrm{H}_{4}(\mathrm{aq})+\mathrm{H}_{2} \mathrm{SO}_{4}(\mathrm{aq}) \rightarrow 2 \mathrm{N}_{2} \mathrm{H}_{5}^{+}(\mathrm{aq})+\mathrm{SO}_{4}^{2-}(\mathrm{aq})$$ What mass of hydrazine reacts with \(250 .\) mL of \(0.146 \mathrm{M} \mathrm{H}_{2} \mathrm{SO}_{4} ?\)

In the photographic developing process, silver bromide is dissolved by adding sodium thiosulfate. $$\operatorname{AgBr}(s)+2 \mathrm{Na}_{2} \mathrm{S}_{2} \mathrm{O}_{3}(\mathrm{aq}) \rightarrow \mathrm{Na}_{3} \mathrm{Ag}\left(\mathrm{S}_{2} \mathrm{O}_{3}\right)_{2}(\mathrm{aq})+\mathrm{NaBr}(\mathrm{aq})$$ If you want to dissolve 0.225 g of AgBr, what volume of \(0.0138 \mathrm{M} \mathrm{Na}_{2} \mathrm{S}_{2} \mathrm{O}_{3},\) in milliliters, should be used?

You can dissolve an aluminum soft drink can in an aqueous base such as potassium hydroxide. $$2 \mathrm{Al}(\mathrm{s})+2 \mathrm{KOH}(\mathrm{aq})+6 \mathrm{H}_{2} \mathrm{O}(\ell) \rightarrow 2 \mathrm{KAl}(\mathrm{OH})_{4}(\mathrm{aq})+3 \mathrm{H}_{2}(\mathrm{g})$$ If you place \(2.05 \mathrm{g}\) of aluminum in a beaker with \(185 \mathrm{mL}\) of \(1.35 \mathrm{M} \mathrm{KOH},\) will any aluminum remain? What mass of \(\mathrm{KAl}(\mathrm{OH})_{4}\) is produced?

What volume of \(0.750 \mathrm{M} \mathrm{Pb}\left(\mathrm{NO}_{3}\right)_{2}\), in milliliters, is required to react completely with 1.00 L of \(2.25 \mathrm{M} \mathrm{NaCl}\) solution? The balanced equation is \(\mathrm{Pb}\left(\mathrm{NO}_{3}\right)_{2}(\mathrm{aq})+2 \mathrm{NaCl}(\mathrm{aq}) \rightarrow \mathrm{PbCl}_{2}(\mathrm{s})+2 \mathrm{NaNO}_{3}(\mathrm{aq})\)

What volume of \(0.125 \mathrm{M}\) oxalic acid, \(\mathrm{H}_{2} \mathrm{C}_{2} \mathrm{O}_{4},\) is required to react with \(35.2 \mathrm{mL}\) of \(0.546 \mathrm{M} \mathrm{NaOH} ?\) $$\mathrm{H}_{2} \mathrm{C}_{2} \mathrm{O}_{4}(\mathrm{aq})+2 \mathrm{NaOH}(\mathrm{aq}) \rightarrow \mathrm{Na}_{2} \mathrm{C}_{2} \mathrm{O}_{4}(\mathrm{aq})+2 \mathrm{H}_{2} \mathrm{O}(\ell)$$

What volume of \(0.812 \mathrm{M} \mathrm{HCl},\) in milliliters, is required to titrate \(1.45 \mathrm{g}\) of \(\mathrm{NaOH}\) to the equivalence point? $$\mathrm{NaOH}(\mathrm{aq})+\mathrm{HCl}(\mathrm{aq}) \rightarrow \mathrm{H}_{2} \mathrm{O}(\ell)+\mathrm{NaCl}(\mathrm{aq})$$

What volume of \(0.955 \mathrm{M} \mathrm{HCl},\) in milliliters, is required to titrate \(2.152 \mathrm{g}\) of \(\mathrm{Na}_{2} \mathrm{CO}_{3}\) to the equivalence point? $$\begin{aligned} \mathrm{Na}_{2} \mathrm{CO}_{3}(\mathrm{aq})+2 \mathrm{HCl}(\mathrm{aq}) \rightarrow & \\\ \mathrm{H}_{2} \mathrm{O}(\ell) &+\mathrm{CO}_{2}(\mathrm{g})+2 \mathrm{NaCl}(\mathrm{aq}) \end{aligned}$$

If \(38.55 \mathrm{mL}\) of HCl is required to titrate \(2.150 \mathrm{g}\) of \(\mathrm{Na}_{2} \mathrm{CO}_{3}\) according to the following equation, what is the concentration (mol/L) of the HCl solution? $$\mathrm{Na}_{2} \mathrm{CO}_{3}(\mathrm{aq})+2 \mathrm{HCl}(\mathrm{aq}) \rightarrow 2 \mathrm{NaCl}(\mathrm{aq})+\mathrm{CO}_{2}(\mathrm{g})+\mathrm{H}_{2} \mathrm{O}(\ell)$$

Potassium hydrogen phthalate, \(\mathrm{KHC}_{8} \mathrm{H}_{4} \mathrm{O}_{4},\) is used to standardize solutions of bases. The acidic anion reacts with strong bases according to the following net ionic equation: $$\mathrm{HC}_{8} \mathrm{H}_{4} \mathrm{O}_{4}^{-}(\mathrm{aq})+\mathrm{OH}^{-}(\mathrm{aq}) \rightarrow \mathrm{C}_{8} \mathrm{H}_{4} \mathrm{O}_{4}^{2-}(\mathrm{aq})+\mathrm{H}_{2} \mathrm{O}(\ell)$$ If a \(0.902-\mathrm{g}\) sample of potassium hydrogen phthalate is dissolved in water and titrated to the equivalence point with \(26.45 \mathrm{mL}\) of \(\mathrm{NaOH}(\mathrm{aq})\) what is the molar concentration of the NaOH?

You have 0.954 g of an unknown acid, \(\mathrm{H}_{2} \mathrm{A},\) which reacts with NaOH according to the balanced equation $$\mathrm{H}_{2} \mathrm{A}(\mathrm{aq})+2 \mathrm{NaOH}(\mathrm{aq}) \rightarrow \mathrm{Na}_{2} \mathrm{A}(\mathrm{aq})+2 \mathrm{H}_{2} \mathrm{O}(\ell)$$ If \(36.04 \mathrm{mL}\) of \(0.509 \mathrm{M} \mathrm{NaOH}\) is required to titrate the acid to the second equivalence point, what is the molar mass of the acid?

An unknown solid acid is either citric acid or tartaric acid. To determine which acid you have, you titrate a sample of the solid with aqueous \(\mathrm{NaOH}\) and from this determine the molar mass of the unknown acid. The appropriate equations are as follows: Citric acid: $$\begin{aligned}\mathrm{H}_{3} \mathrm{C}_{6} \mathrm{H}_{5} \mathrm{O}_{7}(\mathrm{aq})+3 \mathrm{NaOH}(\mathrm{aq}) & \rightarrow \\ 3 \mathrm{H}_{2} \mathrm{O}(\ell) &+\mathrm{Na}_{3} \mathrm{C}_{6} \mathrm{H}_{5} \mathrm{O}_{7}(\mathrm{aq}) \end{aligned}$$ Tartaric acid: $$\begin{aligned}\mathrm{H}_{2} \mathrm{C}_{4} \mathrm{H}_{4} \mathrm{O}_{6}(\mathrm{aq})+2 \mathrm{NaOH}(\mathrm{aq}) \rightarrow & \\\2 \mathrm{H}_{2} \mathrm{O}(\ell) &+\mathrm{Na}_{2} \mathrm{C}_{4} \mathrm{H}_{4} \mathrm{O}_{6}(\mathrm{aq})\end{aligned}$$ A \(0.956-\mathrm{g}\) sample requires \(29.1 \mathrm{mL}\) of \(0.513 \mathrm{M}\) NaOH to consume the acid completely. What is the unknown acid?

To analyze an iron-containing compound, you convert all the iron to \(\mathrm{Fe}^{2+}\) in aqueous solution and then titrate the solution with standardized \(\mathrm{KMnO}_{4} .\) The balanced, net ionic equation is $$\begin{aligned} \mathrm{MnO}_{4}^{-}(\mathrm{aq})+5 \mathrm{Fe}^{2+}(\mathrm{aq})+8 \mathrm{H}_{3} \mathrm{O}^{+}(\mathrm{aq}) & \rightarrow \\ \mathrm{Mn}^{2+}(\mathrm{aq})+5 \mathrm{Fe}^{3+}(\mathrm{aq})+& 12 \mathrm{H}_{2} \mathrm{O}(\ell) \end{aligned}$$ A 0.598 -g sample of the iron-containing compound requires \(22.25 \mathrm{mL}\) of \(0.0123 \mathrm{M} \mathrm{KMnO}_{4}\) for titration to the equivalence point. What is the mass percent of iron in the sample?

Vitamin C has the formula \(\mathrm{C}_{6} \mathrm{H}_{8} \mathrm{O}_{6}\). Besides being an acid, it is a reducing agent. One method for determining the amount of vitamin \(\mathrm{C}\) in a sample is to titrate it with a solution of bromine, \(\mathrm{Br}_{2}\), an oxidizing agent. $$\mathrm{C}_{6} \mathrm{H}_{8} \mathrm{O}_{6}(\mathrm{aq})+\mathrm{Br}_{2}(\mathrm{aq}) \rightarrow 2 \mathrm{HBr}(\mathrm{aq})+\mathrm{C}_{6} \mathrm{H}_{6} \mathrm{O}_{6}(\mathrm{aq})$$ A 1.00 -g "chewable" vitamin C tablet requires \(27.85 \mathrm{mL}\) of \(0.102 \mathrm{M} \mathrm{Br}_{2}\) for titration to the equivalence point. What is the mass of vitamin \(\mathrm{C}\) in the tablet?

A solution of a dye was analyzed by spectrophotometry, and the following calibration data were collected. $$\begin{array}{|c|c|}\hline \text { Dye Concentration } & \begin{array}{c}\text { Absorbance }(A) \\\\\text { at } 475\mathrm{nm} \end{array} \\\\\hline 0.50 \times 10^{-6} \mathrm{M} & 0.24 \\\1.5 \times 10^{-6} \mathrm{M} & 0.36 \\\2.5 \times 10^{-6} \mathrm{M} & 0.44 \\\\\hline 3.5 \times 10^{-6} \mathrm{M} & 0.59 \\\4.5 \times 10^{-6} \mathrm{M} & 0.70\end{array}$$ (a) Construct a calibration plot, and determine the slope and intercept. (b) What is the dye concentration in a solution with \(A=0.52 ?\)

The nitrite ion is involved in the biochemical nitrogen cycle. You can determine the nitrite ion content of a sample using spectrophotometry by first using several organic compounds to form a colored compound from the ion. The following data were collected. $$\begin{array}{|c|c|}\hline \begin{array}{c}\mathrm{NO}_{2}^{-} \text {lon } \\\\\text { Concentration }\end{array} & \begin{array}{c}\text { Absorbance of } \\\\\text { Solution at } 550 \mathrm{nm}\end{array} \\\\\hline 2.00 \times 10^{-6} \mathrm{M} & 0.065 \\\6.00 \times 10^{-6} \mathrm{M} & 0.205 \\\10.00 \times 10^{-6} \mathrm{M} & 0.338 \\ 14.00 \times 10^{-6} \mathrm{M} & 0.474 \\\\\hline 18.00 \times 10^{-6} \mathrm{M} & 0.598 \\\\\hline \text { Unknown solution } & 0.402 \\\\\hline\end{array}$$ (a) Construct a calibration plot, and determine the slope and intercept. (b) What is the nitrite ion concentration in the unknown solution?

Suppose \(16.04 \mathrm{g}\) of benzene, \(\mathrm{C}_{6} \mathrm{H}_{6},\) is burned in oxygen. (a) What are the products of the reaction? (b) Write a balanced equation for the reaction. (c) What mass of \(\mathrm{O}_{2}\), in grams, is required for complete combustion of benzene? (d) What is the total mass of products expected from the combustion of 16.04 g of benzene?

The metabolic disorder diabetes causes a buildup of acetone, \(\mathrm{CH}_{3} \mathrm{COCH}_{3,}\) in the blood. Acetone, a volatile compound, is exhaled, giving the breath of untreated diabetics a distinctive odor. The acetone is produced by a breakdown of fats in a series of reactions. The equation for the last step, the breakdown of acetoacetic acid to give acetone and \(\mathrm{CO}_{2},\) is $$\mathrm{CH}_{3} \mathrm{COCH}_{2} \mathrm{CO}_{2} \mathrm{H} \rightarrow \mathrm{CH}_{3} \mathrm{COCH}_{3}+\mathrm{CO}_{2}$$ What mass of acetone can be produced from \(125 \mathrm{mg}\) of acetoacetic acid?

Your body deals with excess nitrogen by excreting it in the form of urea, \(\mathrm{NH}_{2} \mathrm{CONH}_{2}\). The reaction producing it is the combination of arginine \(\left(\mathrm{C}_{6} \mathrm{H}_{14} \mathrm{N}_{4} \mathrm{O}_{2}\right)\) with water to give urea and ornithine \(\left(\mathrm{C}_{5} \mathrm{H}_{12} \mathrm{N}_{2} \mathrm{O}_{2}\right)\). $$\mathrm{C}_{6} \mathrm{H}_{14} \mathrm{N}_{4} \mathrm{O}_{2}+\mathrm{H}_{2} \mathrm{O} \rightarrow \mathrm{NH}_{2} \mathrm{CONH}_{2}+\mathrm{C}_{5} \mathrm{H}_{12} \mathrm{N}_{2} \mathrm{O}_{2}$$ If you excrete \(95 \mathrm{mg}\) of urea, what mass of arginine must have been used? What mass of ornithine must have been produced?

Some metal halides react with water to produce the metal oxide and the appropriate hydrogen halide (see photo). For example, $$\operatorname{TiCl}_{4}(\ell)+2 \mathrm{H}_{2} \mathrm{O}(\ell) \rightarrow \mathrm{TiO}_{2}(\mathrm{s})+4 \mathrm{HCl}(\mathrm{g})$$ (a) Name the four compounds involved in this reaction. (b) If you begin with \(14.0 \mathrm{mL}\) of \(\mathrm{TiCl}_{4}(d=\) \(1.73 \mathrm{g} / \mathrm{mL}),\) what mass of water, in grams, is required for complete reaction? (c) What mass of each product is expected?

The reaction of \(750 .\) g each of \(\mathrm{NH}_{3}\) and \(\mathrm{O}_{2}\) was found to produce \(562 \text { g of } \mathrm{NO} \text { (see pages } 177-179)\). $$4 \mathrm{NH}_{3}(\mathrm{g})+5 \mathrm{O}_{2}(\mathrm{g}) \rightarrow 4 \mathrm{NO}(\mathrm{g})+6 \mathrm{H}_{2} \mathrm{O}(\ell)$$ (a) What mass of water is produced by this reaction? (b) What mass of \(\mathrm{O}_{2}\) is required to consume \(750 . \mathrm{g}\) of \(\mathrm{NH}_{3} ?\)

Sodium azide, an explosive chemical used in automobile airbags, is made by the following reaction: $$\mathrm{NaNO}_{3}+3 \mathrm{NaNH}_{2} \rightarrow \mathrm{NaN}_{3}+3 \mathrm{NaOH}+\mathrm{NH}_{3}$$ If you combine \(15.0 \mathrm{g}\) of \(\mathrm{NaNO}_{3}\) with \(15.0 \mathrm{g}\) of \(\mathrm{NaNH}_{2},\) what mass of \(\mathrm{NaN}_{3}\) is produced?

Iodine is made by the following reaction $$\begin{array}{l}\text { 2 } \mathrm{NaIO}_{3}(\mathrm{aq})+5 \mathrm{NaHSO}_{3}(\mathrm{aq}) \rightarrow \\\\\quad 3 \mathrm{NaHSO}_{4}(\mathrm{aq})+2 \mathrm{Na}_{2} \mathrm{SO}_{4}(\mathrm{aq})+\mathrm{H}_{2} \mathrm{O}(\ell)+\mathrm{I}_{2}(\mathrm{aq}) \end{array}$$ (a) Name the two reactants. (b) If you wish to prepare \(1.00 \mathrm{kg}\) of \(\mathrm{I}_{2},\) what masses of \(\mathrm{NaIO}_{3}\) and \(\mathrm{NaHSO}_{3}\) are required? (c) What is the theoretical yield of \(\mathrm{I}_{2}\) if you mixed \(15.0 \mathrm{g}\) of \(\mathrm{NaIO}_{3}\) with \(125 \mathrm{mL}\) of \(0.853 \mathrm{M}\) \(\mathrm{NaHSO}_{3} ?\)

Saccharin, an artificial sweetener, has the formula \(\mathrm{C}_{7} \mathrm{H}_{5} \mathrm{NO}_{3} \mathrm{S}\). Suppose you have a sample of a saccharin-containing sweetener with a mass of \(0.2140 \mathrm{g} .\) After decomposition to free the sulfur and convert it to the \(\mathrm{SO}_{4}^{2-}\) ion, the sulfate ion is trapped as water-insoluble \(\mathrm{BaSO}_{4}\) (Figure 4.4). The quantity of \(\mathrm{BaSO}_{4}\) obtained is 0.2070 g. What is the mass percent of saccharin in the sample of sweetener?

Boron forms a series of compounds with hydrogen, all with the general formula \(\mathrm{B}_{x} \mathrm{H}_{y}\). $$\mathrm{B}_{x} \mathrm{H}_{y}(\mathrm{s})+\text { excess } \mathrm{O}_{2}(\mathrm{g}) \rightarrow \frac{x}{2} \mathrm{B}_{2} \mathrm{O}_{3}(\mathrm{s})+\frac{\gamma}{2} \mathrm{H}_{2} \mathrm{O}(\mathrm{g})$$ If \(0.148 \mathrm{g}\) of one of these compounds gives \(0.422 \mathrm{g}\) of \(\mathrm{B}_{2} \mathrm{O}_{3}\) when burned in excess \(\mathrm{O}_{2},\) what is its empirical formula?

Silicon and hydrogen form a series of compounds with the general formula \(\mathrm{Si}_{x} \mathrm{H}_{y}\). To find the formula of one of them, a 6.22 -g sample of the compound is burned in oxygen. All of the Si is converted to \(11.64 \mathrm{g}\) of \(\mathrm{SiO}_{2},\) and all of the H is converted to \(6.980 \mathrm{g}\) of \(\mathrm{H}_{2} \mathrm{O}\). What is the empirical formula of the silicon compound?

Menthol, from oil of mint, has a characteristic odor. The compound contains only \(\mathrm{C}, \mathrm{H},\) and \(\mathrm{O}\) If \(95.6 \mathrm{mg}\) of menthol burns completely in \(\mathrm{O}_{2}\) and gives \(269 \mathrm{mg}\) of \(\mathrm{CO}_{2}\) and \(111 \mathrm{mg}\) of \(\mathrm{H}_{2} \mathrm{O}\) what is the empirical formula of menthol?

Benzoquinone, a chemical used in the dye industry and in photography, is an organic compound containing only \(\mathrm{C}, \mathrm{H},\) and \(\mathrm{O}\). What is the empirical formula of the compound if \(0.105 \mathrm{g}\) of the compound gives 0.257 g of \(\mathrm{CO}_{2}\) and \(0.0350 \mathrm{g}\) of \(\mathrm{H}_{2} \mathrm{O}\) when burned completely in oxygen?

Aqueous solutions of iron(II) chloride and sodium sulfide react to form iron(II) sulfide and sodium chloride. (a) Write the balanced equation for the reaction. (b) If you combine \(40 .\) g each of \(\mathrm{Na}_{2} \mathrm{S}\) and \(\mathrm{FeCl}_{2}\) what is the limiting reactant? (c) What mass of FeS is produced? (d) What mass of \(\mathrm{Na}_{2} \mathrm{S}\) or \(\mathrm{FeCl}_{2}\) remains after the reaction? (e) What mass of \(\mathrm{FeCl}_{2}\) is required to react completely with \(40 .\) g of \(\mathrm{Na}_{2} \mathrm{S}\) ?

Sulfuric acid can be prepared starting with the sulfide ore, cuprite \(\left(\mathrm{Cu}_{2} \mathrm{S}\right) .\) If each \(\mathrm{S}\) atom in \(\mathrm{Cu}_{2} \mathrm{S}\) leads to one molecule of \(\mathrm{H}_{2} \mathrm{SO}_{4},\) what is the theoretical yield of \(\mathrm{H}_{2} \mathrm{SO}_{4}\) from \(3.00 \mathrm{kg}\) of \(\mathrm{Cu}_{2} \mathrm{S}\) ?

In an experiment, 1.056 g of a metal carbonate, containing an unknown metal \(\mathrm{M},\) is heated to give the metal oxide and \(0.376 \mathrm{g} \mathrm{CO}_{2}\). $$\mathrm{MCO}_{3}(\mathrm{s})+\text { heat } \rightarrow \mathrm{MO}(\mathrm{s})+\mathrm{CO}_{2}(\mathrm{g})$$ What is the identity of the metal \(\mathrm{M}\) ? (a) \(\mathrm{M}=\mathrm{Ni}\) (b) \(\mathrm{M}=\mathrm{Cu}\) (c) \(\mathrm{M}=\mathrm{Zn}\) (d) \(\mathrm{M}=\mathrm{Ba}\)

An unknown metal reacts with oxygen to give the metal oxide, \(\mathrm{MO}_{2}\). Identify the metal if a \(0.356-\mathrm{g}\) sample of the metal produces \(0.452 \mathrm{g}\) of the metal oxide.

Titanium(IV) oxide, \(\mathrm{TiO}_{2}\), is heated in hydrogen gas to give water and a new titanium oxide, \(\mathrm{Ti}_{x} \mathrm{O}_{y},\) If \(1.598 \mathrm{g}\) of \(\mathrm{TiO}_{2}\) produces \(1.438 \mathrm{g}\) of \(\mathrm{Ti}_{x} \mathrm{O}_{y},\) what is the empirical formula of the new oxide?

Potassium perchlorate is prepared by the following sequence of reactions: $$\mathrm{Cl}_{2}(\mathrm{g})+2 \mathrm{KOH}(\mathrm{aq}) \rightarrow \mathrm{KCl}(\mathrm{aq})+\mathrm{KClO}(\mathrm{aq})+\mathrm{H}_{2} \mathrm{O}(\ell)$$ $$\begin{aligned}3 \mathrm{KClO}(\mathrm{aq}) & \rightarrow 2 \mathrm{KCl}(\mathrm{aq})+\mathrm{KClO}_{3}(\mathrm{aq}) \\\4 \mathrm{KClO}_{3}(\mathrm{aq}) & \rightarrow 3 \mathrm{KClO}_{4}(\mathrm{aq})+\mathrm{KCl}(\mathrm{aq})\end{aligned}$$ What mass of \(\mathrm{Cl}_{2}(\mathrm{g})\) is required to produce \(234 \mathrm{kg}\) of \(\mathrm{KClO}_{4} ?\)

Commercial sodium "hydrosulfite" is \(90.1 \%\) \(\mathrm{Na}_{2} \mathrm{S}_{2} \mathrm{O}_{4} .\) The sequence of reactions used to prepare the compound is $$\mathrm{Zn}(\mathrm{s})+2 \mathrm{SO}_{2}(\mathrm{g}) \rightarrow \mathrm{ZnS}_{2} \mathrm{O}_{4}(\mathrm{s})$$ $$\mathrm{ZnS}_{2} \mathrm{O}_{4}(\mathrm{s})+\mathrm{Na}_{2} \mathrm{CO}_{3}(\mathrm{aq}) \rightarrow \mathrm{ZnCO}_{3}(\mathrm{s})+\mathrm{Na}_{2} \mathrm{S}_{2} \mathrm{O}_{4}(\mathrm{aq})$$ (a) What mass of pure \(\mathrm{Na}_{2} \mathrm{S}_{2} \mathrm{O}_{4}\) can be prepared from \(125 \mathrm{kg}\) of \(\mathrm{Zn}, 500 .\) g of \(\mathrm{SO}_{2},\) and an excess of \(\mathrm{Na}_{2} \mathrm{CO}_{3} ?\) (b) What mass of the commercial product would contain the \(\mathrm{Na}_{2} \mathrm{S}_{2} \mathrm{O}_{4}\) produced using the amounts of reactants in part (a)?

What mass of lime, \(\mathrm{CaO},\) can be obtained by heating \(125 \mathrm{kg}\) of limestone that is \(95.0 \%\) by mass \(\mathrm{CaCO}_{3} ?\) $$\mathrm{CaCO}_{3}(\mathrm{s}) \rightarrow \mathrm{CaO}(\mathrm{s})+\mathrm{CO}_{2}(\mathrm{g})$$

The elements silver, molybdenum, and sulfur combine to form \(\mathrm{Ag}_{2} \mathrm{MoS}_{4} .\) What is the maximum mass of \(\mathrm{Ag}_{2} \mathrm{MoS}_{4}\) that can be obtained if \(8.63 \mathrm{g}\) of silver, 3.36 g of molybdenum, and 4.81 g of sulfur are combined? (Hint: What is the limiting reactant?)

A mixture of butene, \(\mathrm{C}_{4} \mathrm{H}_{8},\) and butane, \(\mathrm{C}_{4} \mathrm{H}_{10}\) is burned in air to give \(\mathrm{CO}_{2}\) and water. Suppose you burn 2.86 g of the mixture and obtain \(8.80 \mathrm{g}\) of \(\mathrm{CO}_{2}\) and \(4.14 \mathrm{g}\) of \(\mathrm{H}_{2} \mathrm{O}\). What are the mass percentages of butene and butane in the mixture?

Cloth can be waterproofed by coating it with a silicone layer. This is done by exposing the cloth to \(\left(\mathrm{CH}_{3}\right)_{2} \mathrm{SiCl}_{2}\) vapor. The silicon compound reacts with OH groups on the cloth to form a waterproofing film (density \(=1.0 \mathrm{g} / \mathrm{cm}^{3}\) ) of \(\left[\left(\mathrm{CH}_{3}\right)_{2} \mathrm{SiO}\right]_{n},\) where \(n\) is a large integer number. $$\begin{aligned}&n\left(\mathrm{CH}_{3}\right)_{2} \mathrm{SiCl}_{2}+2 n \mathrm{OH}^{-} \rightarrow\\\&&2 n \mathrm{Cl}^{-}+n \mathrm{H}_{2} \mathrm{O}+\left[\left(\mathrm{CH}_{3}\right)_{2} \mathrm{SiO}\right]_{n} \end{aligned}$$ The coating is added layer by layer, with each layer of \(\left[\left(\mathrm{CH}_{3}\right)_{2} \mathrm{SiO}\right]_{n}\) being 0.60 nm thick. Suppose you want to waterproof a piece of cloth that is 3.00 square meters, and you want 250 layers of waterproofing compound on the cloth. What mass of \(\left(\mathrm{CH}_{3}\right)_{2} \mathrm{SiCl}_{2}\) do you need?

Copper metal can be prepared by roasting copper ore, which can contain cuprite \(\left(\mathrm{Cu}_{2} \mathrm{S}\right)\) and copper(II) sulfide. $$\begin{aligned}\mathrm{Cu}_{2} \mathrm{S}(\mathrm{s})+\mathrm{O}_{2}(\mathrm{g}) & \rightarrow 2 \mathrm{Cu}(\mathrm{s})+\mathrm{SO}_{2}(\mathrm{g}) \\\\\mathrm{CuS}(\mathrm{s})+\mathrm{O}_{2}(\mathrm{g}) & \rightarrow \mathrm{Cu}(\mathrm{s})+\mathrm{SO}_{2}(\mathrm{g})\end{aligned}$$ Suppose an ore sample contains \(11.0 \%\) impurity in addition to a mixture of CuS and \(\mathrm{Cu}_{2} \mathrm{S}\). Heating \(100.0 \mathrm{g}\) of the mixture produces \(75.4 \mathrm{g}\) of copper metal with a purity of \(89.5 \% .\) What is the weight percent of CuS in the ore? The weight percent of \(\mathrm{Cu}_{2} \mathrm{S} ?\)

An Alka-Seltzer tablet contains exactly \(100 . \mathrm{mg}\) of citric acid, \(\mathrm{H}_{3} \mathrm{C}_{6} \mathrm{H}_{5} \mathrm{O}_{7},\) plus some sodium bicarbonate. What mass of sodium bicarbonate is required to consume \(100 .\) mg of citric acid by the following reaction? $$\begin{aligned}\mathrm{H}_{3} \mathrm{C}_{6} \mathrm{H}_{5} \mathrm{O}_{7}(\mathrm{aq})+3 \mathrm{NaHCO}_{3}(\mathrm{aq}) \rightarrow & \\\3 \mathrm{H}_{2} \mathrm{O}(\ell)+3 \mathrm{CO}_{2}(\mathrm{g}) &+\mathrm{Na}_{3} \mathrm{C}_{6} \mathrm{H}_{5} \mathrm{O}_{7}(\mathrm{aq})\end{aligned}$$

Sodium bicarbonate and acetic acid react according to the equation $$\begin{aligned}\mathrm{NaHCO}_{3}(\mathrm{aq})+\mathrm{CH}_{3} \mathrm{CO}_{2} \mathrm{H}(\mathrm{aq}) & \rightarrow \\\\\mathrm{NaCH}_{3} \mathrm{CO}_{2}(\mathrm{aq}) &+\mathrm{CO}_{2}(\mathrm{g})+\mathrm{H}_{2} \mathrm{O}(\ell)\end{aligned}$$ What mass of sodium acetate can be obtained from mixing \(15.0 \mathrm{g}\) of \(\mathrm{NaHCO}_{3}\) with \(125 \mathrm{mL}\) of \(0.15 \mathrm{M}\) acetic acid?