Problem 140
An ore of barium contains \(\mathrm{BaCO}_{3}\). A 1.542 g sample of the ore was treated with \(\mathrm{HCl}\) to dissolve the \(\mathrm{BaCO}_{3}\). The resulting solution was filtered to remove insoluble material and then treated with \(\mathrm{H}_{2} \mathrm{SO}_{4}\) to precipitate \(\mathrm{BaSO}_{4}\). The precipi- (a) How tate was filtered, dried, and found to weigh \(1.159 \mathrm{~g}\). many moles of barium were in the ore sample? (b) How many grams of barium were in the ore sample? (c) What is the percentage by mass of barium in the ore? (d) If the molarity and volume of the sulfuric acid needed for the precipitation was noted, could you get the same answers?
Problem 141
If a solution of sodium phosphate (also known as trisodium phosphate, or \(\mathrm{TSP}\) ), \(\mathrm{Na}_{3} \mathrm{PO}_{4}\), is poured into seawater, precipitates of calcium phosphate and magnesium phosphate are formed. (Magnesium and calcium ions are among the principal ions found in seawater.) Write net ionic equations for these reactions.
Problem 142
With which of the following will the weak acid \(\mathrm{HCHO}_{2}\) react? For those with which there is a reaction, write the formulas of the products. (a) \(\mathrm{KOH},\) (b) \(\mathrm{MgO},\) (c) \(\mathrm{NH}_{3}\)
Problem 143
Suppose that \(25.0 \mathrm{~mL}\) of \(0.440 \mathrm{M} \mathrm{NaCl}\) is added to \(25.0 \mathrm{~mL}\) of \(0.320 \mathrm{MAgNO}_{3}\) (a) How many moles of \(\mathrm{AgCl}\) would precipitate? (b) What would be the concentrations of each of the ions in the reaction mixture after the reaction?
Problem 145
Classify each of the following as a strong electrolyte, weak electrolyte, or nonelectrolyte. (a) \(\mathrm{LiBr}\) (b) glucose (a sugar) (c) \(\mathrm{Ca}(\mathrm{OH})_{2}\) (d) \(\mathrm{NH}_{3}\)
Problem 146
Aspirin is a monoprotic acid called acetylsalicylic acid Its formula is \(\mathrm{HC}_{9} \mathrm{H}_{7} \mathrm{O}_{4}\). A certain pain reliever was analyzed for aspirin by dissolving \(0.118 \mathrm{~g}\) of it in water and titrating it with \(0.0300 \mathrm{M} \mathrm{KOH}\) solution. The titration required \(14.76 \mathrm{~mL}\) of base. What is the percentage by weight of aspirin in the drug?
Problem 148
How many milliliters of \(0.10 \mathrm{M} \mathrm{HCl}\) must be added to \(50.0 \mathrm{~mL}\) of \(0.40 \mathrm{M} \mathrm{HCl}\) to give a final solution that has a molarity of \(0.25 M ?\)
Problem 151
Qualitative analysis of an unknown acid found only carbon, hydrogen, and oxygen. In a quantitative analysis, a \(10.46 \mathrm{mg}\) sample was burned in oxygen and gave 22.17 \(\mathrm{mg} \mathrm{CO}_{2}\) and \(3.40 \mathrm{mg} \mathrm{H}_{2} \mathrm{O}\). The molecular mass was de- termined to be \(166 \mathrm{~g} \mathrm{~mol}^{-1}\). When a \(0.1680 \mathrm{~g}\) sample of the acid was titrated with \(0.1250 \mathrm{M} \mathrm{NaOH},\) the end point was reached after \(16.18 \mathrm{~mL}\) of the base had been added. (a) What is the molecular formula for the acid? (b) Is the acid mono-, \(\mathrm{di}\) -, or triprotic?
Problem 152
A mixture was known to contain both \(\mathrm{KNO}_{3}\) and \(\mathrm{K}_{2} \mathrm{SO}_{3}\). To \(0.486 \mathrm{~g}\) of the mixture, dissolved in enough water to give \(50.00 \mathrm{~mL}\) of solution, was added \(50.00 \mathrm{~mL}\) of \(0.150 \mathrm{M} \mathrm{HCl}\) (an excess of \(\mathrm{HCl}\) ). The reaction mixture was heated to drive off all of the \(\mathrm{SO}_{2}\), and then \(25.00 \mathrm{~mL}\) of the reaction mixture was titrated with \(0.100 \mathrm{MKOH}\) The titration required \(13.11 \mathrm{~mL}\) of the \(\mathrm{KOH}\) solution to reach an end point. What was the percentage by mass of \(\mathrm{K}_{2} \mathrm{SO}_{3}\) in the original mixture of \(\mathrm{KNO}_{3}\) and \(\mathrm{K}_{2} \mathrm{SO}_{3}\) ?
Problem 163
Carbon dioxide is one obvious contributor to excessive global warming. What is your plan for controlling \(\mathrm{CO}_{2}\) emissions? What are the advantages and disadvantages of your plan?
