Problem 148
A transition metal \(X\) forms an oxide of formula \(\mathrm{X}_{2} \mathrm{O}_{3} .\) It is found that only \(50 \%\) of \(\mathrm{X}\) atoms in this compound are in the +3 oxidation state. The only other stable oxidation states of \(X\) are +2 and +5 . What percentage of \(\mathrm{X}\) atoms are in the +2 oxidation state in this compound?
Problem 149
What volume of a solution of ethanol, \(\mathrm{C}_{2} \mathrm{H}_{6} \mathrm{O},\) that is \(94.0 \%\) ethanol by mass contains \(0.200 \mathrm{~mol} \mathrm{C}_{2} \mathrm{H}_{6} \mathrm{O}\) ? The density of the solution is \(0.807 \mathrm{~g} / \mathrm{mL}\) 4.150 What volume of a solution of ethylene glycol, \(\mathrm{C}_{2} \mathrm{H}_{6} \mathrm{O}_{2}\), that is \(56.0 \%\) ethylene glycol by mass contains \(0.350 \mathrm{~mol}\) \(\mathrm{C}_{2} \mathrm{H}_{6} \mathrm{O}_{2} ?\) The density of the solution is \(1.072 \mathrm{~g} / \mathrm{mL}\)
Problem 150
What volume of a solution of ethylene glycol, \(\mathrm{C}_{2} \mathrm{H}_{6} \mathrm{O}_{2}\), that is \(56.0 \%\) ethylene glycol by mass contains \(0.350 \mathrm{~mol}\) \(\mathrm{C}_{2} \mathrm{H}_{6} \mathrm{O}_{2} ?\) The density of the solution is \(1.072 \mathrm{~g} / \mathrm{mL}\)
Problem 151
A 10.0-mL sample of potassium iodide solution was analyzed by adding an excess of silver nitrate solution to produce silver iodide crystals, which were filtered from the solution. $$ \mathrm{KI}(a q)+\mathrm{AgNO}_{3}(a q) \longrightarrow \mathrm{KNO}_{3}(a q)+\mathrm{AgI}(s) $$ If \(2.183 \mathrm{~g}\) of silver iodide was obtained, what was the molarity of the original KI solution?
Problem 152
A 25.0-mL sample of sodium sulfate solution was analyzed by adding an excess of barium chloride solution to produce barium sulfate crystals, which were filtered from the solution. \(\mathrm{Na}_{2} \mathrm{SO}_{4}(a q)+\mathrm{BaCl}_{2}(a q) \longrightarrow 2 \mathrm{NaCl}(a q)+\mathrm{BaSO}_{4}(s)\) If \(5.719 \mathrm{~g}\) of barium sulfate was obtained, what was the molarity of the original \(\mathrm{Na}_{2} \mathrm{SO}_{4}\) solution?
Problem 153
A metal, M, was converted to the sulfate, \(\mathrm{M}_{2}\left(\mathrm{SO}_{4}\right)_{3}\). Then a solution of the sulfate was treated with barium chloride to give barium sulfate crystals, which were filtered off. \(\mathrm{M}_{2}\left(\mathrm{SO}_{4}\right)_{3}(a q)+3 \mathrm{BaCl}_{2}(a q) \longrightarrow\) $$ 2 \mathrm{MCl}_{3}(a q)+3 \mathrm{BaSO}_{4}(s) $$ If \(1.200 \mathrm{~g}\) of the metal gave \(6.026 \mathrm{~g}\) of barium sulfate, what is the atomic weight of the metal? What is the metal?
Problem 154
A metal, \(\mathrm{M}\), was converted to the chloride \(\mathrm{MCl}_{2}\). Then a solution of the chloride was treated with silver nitrate to give silver chloride crystals, which were filtered from the solution. \(\mathrm{MCl}_{2}(a q)+2 \mathrm{AgNO}_{3}(a q) \longrightarrow\) $$ \mathrm{M}\left(\mathrm{NO}_{3}\right)_{2}(a q)+2 \mathrm{AgCl}(s) $$ If \(2.434 \mathrm{~g}\) of the metal gave \(7.964 \mathrm{~g}\) of silver chloride, what is the atomic weight of the metal? What is the metal?
Problem 155
Phosphoric acid is prepared by dissolving phosphorus(V) oxide, \(\mathrm{P}_{4} \mathrm{O}_{10}\), in water. What is the balanced equation for this reaction? How many grams of \(\mathrm{P}_{4} \mathrm{O}_{10}\) are required to make \(1.19 \mathrm{~L}\) of aqueous solution containing \(5.50 \%\) phosphoric acid by mass? The density of the solution is \(1.025 \mathrm{~g} / \mathrm{mL}\)
Problem 156
Iron(III) chloride can be prepared by reacting iron metal with chlorine. What is the balanced equation for this reaction? How many grams of iron are required to make \(3.00 \mathrm{~L}\) of aqueous solution containing \(9.00 \%\) iron(III) chloride by mass? The density of the solution is \(1.067 \mathrm{~g} / \mathrm{mL}\).
Problem 157
An alloy of aluminum and magnesium was treated with sodium hydroxide solution, in which only aluminum reacts. $$ 2 \mathrm{Al}(s)+2 \mathrm{NaOH}(a q)+6 \mathrm{H}_{2} \mathrm{O}(l) \longrightarrow $$ If a sample of alloy weighing \(1.225 \mathrm{~g}\) gave \(0.1093 \mathrm{~g}\) of hydrogen, what is the percentage of aluminum in the alloy?
