Chapter 3

What is the definition of the mole?

Write the following as balanced chemical equations. (a) Calcium hydroxide reacts with hydrogen chloride to form calcium chloride and water. (b) Silver nitrate and calcium chloride react to form calcium nitrate and silver chloride. (c) Lead(II) nitrate reacts with sodium sulfate to form lead(II) sulfate and sodium nitrate. (d) Iron(III) oxide and carbon react to form iron and carbon dioxide.

Which contains more molecules: \(2.5 \mathrm{~mol}\) of \(\mathrm{H}_{2} \mathrm{O}\) or \(2.5 \mathrm{~mol}\) of \(\mathrm{H}_{2}\) ? Which contains more atoms? Which weighs more?

Write the following as balanced chemical equations. (a) Sulfur dioxide reacts with oxygen to form sulfur trioxide. (b) Sodium bicarbonate and sulfuric acid react to form sodium sulfate, water, and carbon dioxide. (c) Tetraphosphorous decaoxide and water react together and form phosphoric acid. (d) Butane reacts with oxygen to form carbon dioxide and water.

What information is required to convert grams of a substance into molecules of that same substance?

How many moles of iron atoms are in one mole of \(\mathrm{Fe}_{2} \mathrm{O}_{3}\) ? How many iron atoms are in one mole of \(\mathrm{Fe}_{2} \mathrm{O}_{3}\) ?

Write all the mole-to-mole conversion factors that can be written based on the following chemical formulas: (a) \(\mathrm{SO}_{2}\), (b) \(\mathrm{As}_{2} \mathrm{O}_{3}\) (c) \(\mathrm{K}_{2} \mathrm{SO}_{4}\) (d) \(\mathrm{Na}_{2} \mathrm{HPO}_{4}\)

What information is required to convert grams of a substance into moles of that same substance?

The atomic mass of aluminum is 26.98 . What specific conversion factors does this value make available for relating a mass of aluminum (in grams) and a quantity of aluminum given in moles?

In general, what fundamental information, obtained from experimental measurements, is required to calculate the empirical formula of a compound?

Why can percentage composition be used to determine empirical formula, but not molecular formula?

Why can percentage composition be used to determine empirical formula, but not molecular formula?

When balancing a chemical reaction, what numbers can be changed? When balancing chemical equations which scientific law is being used?

Give a step-by-step procedure for estimating the number of grams of \(A\) required to completely react with 10 moles of \(B\), given the following information: \(A\) and \(B\) react to form \(A_{5} B_{2}\) \(A\) has a molecular mass of \(100.0 . B\) has a molecular mass of 200.0 There are \(6.02 \times 10^{23}\) molecules of \(A\) in a mole of \(A\). Which of these pieces of information weren't needed?

A mixture of \(0.020 \mathrm{~mol}\) of \(\mathrm{Mg}\) and \(0.020 \mathrm{~mol}\) of \(\mathrm{Cl}_{2}\) reacted completely to form \(\mathrm{MgCl}_{2}\) according to the equation $$ \mathrm{Mg}+\mathrm{Cl}_{2} \longrightarrow \mathrm{MgCl}_{2} $$ What information describes the stoichiometry of this reaction? What information gives the scale of the reaction?

In a report to a supervisor, a chemist described an experiment in the following way: " \(0.0800 \mathrm{~mol}\) of \(\mathrm{H}_{2} \mathrm{O}_{2}\) decomposed into \(0.0800 \mathrm{~mol}\) of \(\mathrm{H}_{2} \mathrm{O}\) and \(0.0400 \mathrm{~mol}\) of \(\mathrm{O}_{2}\)." Express the chemistry and stoichiometry of this reaction by a conventional chemical equation.

What is a limiting reactant? And why does the limiting reactant determine how much product is formed?

Explain why the actual yield is always less than the theoretical yield.

Determine the mass in grams of each of the following: (a) \(1.35 \mathrm{~mol} \mathrm{Fe}\) (c) \(0.876 \mathrm{~mol} \mathrm{Ca}\) (b) \(24.5 \mathrm{~mol} \mathrm{O}\)

Determine the mass in grams of the following: (a) \(0.546 \mathrm{~mol} \mathrm{~S}\) (c) \(8.11 \mathrm{~mol} \mathrm{Al}\) (b) \(3.29 \mathrm{~mol} \mathrm{~N}\)

Calculate the mass in grams of the following. (a) \(1.25 \mathrm{~mol} \mathrm{Ca}_{3}\left(\mathrm{PO}_{4}\right)_{2}\) (b) \(0.600 \mu \mathrm{mol} \mathrm{C}_{4} \mathrm{H}_{10}\) (c) \(0.625 \mathrm{mmol}\) iron(III) nitrate (d) 1.45 mol ammonium carbonate

Calculate the number of moles of each compound in the following samples. (a) \(1.56 \mathrm{ng} \mathrm{NH}_{3}\) (c) \(21.5 \mathrm{~g}\) calcium carbonate (b) \(6.98 \mu \mathrm{g} \mathrm{Na}_{2} \mathrm{CrO}_{4}\) (d) \(16.8 \mathrm{~g}\) strontium nitrate

Calculate the number of moles of each compound in the following samples. (a) \(4.29 \mathrm{~g} \mathrm{H}_{2} \mathrm{O}_{2}\) (c) \(9.36 \mathrm{~g}\) calcium hydroxide (b) \(4.65 \mathrm{mg} \mathrm{NaAuCl}_{4}\) (d) \(38.2 \mathrm{~kg}\) lead \((\mathrm{II})\) sulfate

How many moles of nickel are in \(17.7 \mathrm{~g}\) of \(\mathrm{Ni}\) ?

How many moles of chromium are in \(85.7 \mathrm{~g}\) of \(\mathrm{Cr}\) ?

How many moles of tantalum atoms correspond to \(1.56 \times 10^{21}\) atoms of tantalum?

How many moles of iodine molecules correspond to \(1.80 \times 10^{24}\) molecules of \(\mathrm{I}_{2} ?\)

How many atoms are in \(6.00 \mathrm{~g}\) of carbon-12?

How many atoms are in \(1.50 \mathrm{~mol}\) of carbon-12? How many grams does this much carbon-12 weigh?

Sucrose (table sugar) has the formula \(\mathrm{C}_{12} \mathrm{H}_{22} \mathrm{O}_{11} .\) In this compound, what is the (a) atom ratio of \(\mathrm{C}\) to \(\mathrm{H}\) ? (c) atom ratio of \(\mathrm{H}\) to \(\mathrm{O}\) ? (b) mole ratio of \(\mathrm{C}\) to \(\mathrm{O}\) ? (d) mole ratio of \(\mathrm{H}\) to \(\mathrm{O}\) ?

Nail polish remover is usually the volatile liquid ethyl acetate, \(\mathrm{CH}_{3} \mathrm{COOC}_{2} \mathrm{H}_{5} .\) In this compound, what is the (a) atom ratio of \(\mathrm{C}\) to \(\mathrm{O}\) ? (c) atom ratio of \(\mathrm{C}\) to \(\mathrm{H}\) ? (b) mole ratio of \(\mathrm{C}\) to \(\mathrm{O}\) ? (d) mole ratio of \(\mathrm{C}\) to \(\mathrm{H}\) ?

How many moles of \(\mathrm{Bi}\) atoms are needed to combine with \(1.58 \mathrm{~mol}\) of \(\mathrm{O}\) atoms to make \(\mathrm{Bi}_{2} \mathrm{O}_{3}\) ?

How many moles of vanadium atoms, \(\mathrm{V},\) are needed to combine with 0.565 mol of \(\mathrm{O}\) atoms to make vanadium pentoxide, \(\mathrm{V}_{2} \mathrm{O}_{5} ?\)

How many moles of \(\mathrm{Cr}\) are in \(2.16 \mathrm{~mol}\) of \(\mathrm{Cr}_{2} \mathrm{O}_{3}\) ?

How many moles of \(\mathrm{O}\) atoms are in \(4.25 \mathrm{~mol}\) of calcium carbonate, \(\mathrm{CaCO}_{3}\), the chief constituent of seashells?

Aluminum sulfate, \(\mathrm{Al}_{2}\left(\mathrm{SO}_{4}\right)_{3}\), is a compound used in sewage treatment plants to remove pollutants by causing them to precipitate. (a) Construct a pair of conversion factors that relate moles of aluminum to moles of sulfur for this compound. (b) Construct a pair of conversion factors that relate moles of sulfur to moles of \(\mathrm{Al}_{2}\left(\mathrm{SO}_{4}\right)_{3}\). (c) How many moles of \(\mathrm{Al}\) are in a sample of this compound if the sample also contains \(0.900 \mathrm{~mol} \mathrm{~S} ?\) (d) How many moles of \(S\) are in \(1.16 \mathrm{~mol} \mathrm{Al}_{2}\left(\mathrm{SO}_{4}\right)_{3}\) ?

How many moles of \(S\) are needed to combine with 0.225 mol Al to give \(\mathrm{Al}_{2} \mathrm{~S}_{3}\) ?

How many moles of \(\mathrm{UF}_{6}\) would have to be decomposed to provide enough fluorine to prepare \(1.25 \mathrm{~mol}\) of \(\mathrm{CF}_{4} ?\) (Assume sufficient carbon is available.)

How many moles of \(\mathrm{Fe}_{3} \mathrm{O}_{4}\) are required to supply enough iron to prepare \(0.260 \mathrm{~mol} \mathrm{Fe}_{2} \mathrm{O}_{3}\) ? (Assume sufficient oxygen is available.)

How many atoms of carbon are combined with 4.13 moles of hydrogen atoms in a sample of the compound propane, \(\mathrm{C}_{3} \mathrm{H}_{8} ?\) (Propane is used as the fuel in gas barbecues.)

How many atoms of hydrogen are found in \(2.31 \mathrm{~mol}\) of propane, \(\mathrm{C}_{3} \mathrm{H}_{8} ?\)

What is the total number of \(\mathrm{C}, \mathrm{H},\) and \(\mathrm{O}\) atoms in 0.260 moles of glucose, \(\mathrm{C}_{6} \mathrm{H}_{12} \mathrm{O}_{6} ?\)

What is the total number of \(\mathrm{N}, \mathrm{H},\) and \(\mathrm{O}\) atoms \(\mathrm{in}\) \(0.356 \mathrm{~mol}\) of ammonium nitrate, \(\mathrm{NH}_{4} \mathrm{NO}_{3}\), an important fertilizer?

Calcium carbide, \(\mathrm{CaC}_{2},\) was once used to make signal flares for ships. Water dripped onto \(\mathrm{CaC}_{2}\) reacts to give acetylene \(\left(\mathrm{C}_{2} \mathrm{H}_{2}\right)\), which burns brightly. One sample of \(\mathrm{CaC}_{2}\) contains \(0.150 \mathrm{~mol}\) of carbon. How many moles and how many grams of calcium are also in the sample?

Iodized salt contains a trace amount of calcium iodate, \(\mathrm{Ca}\left(\mathrm{IO}_{3}\right)_{2},\) to help prevent a thyroid condition called goiter. How many moles of iodine atoms are in \(0.500 \mathrm{~mol}\) of \(\mathrm{Ca}\left(\mathrm{IO}_{3}\right)_{2}\) ? How many grams of calcium iodate are needed to supply this much iodine?

How many moles of nitrogen, \(\mathrm{N},\) are in \(0.556 \mathrm{~mol}\) of ammonium nitrate? How many grams of this compound supply this much nitrogen?

How many kilograms of a fertilizer made of pure \(\left(\mathrm{NH}_{4}\right)_{2} \mathrm{CO}_{3}\) would be required to supply 1 kilogram of nitrogen to the soil?

Calculate the percentage composition by mass for each element in the following: (a) \(\mathrm{NH}_{4} \mathrm{H}_{2} \mathrm{PO}_{4}\) (c) sodium dihydrogen phosphate (b) \(\left(\mathrm{CH}_{3}\right)_{2} \mathrm{CO}\) (d) calcium sulfate dihydrate

Which has a higher percentage of oxygen: morphine \(\left(\mathrm{C}_{17} \mathrm{H}_{19} \mathrm{NO}_{3}\right)\) or heroin \(\left(\mathrm{C}_{21} \mathrm{H}_{23} \mathrm{NO}_{5}\right) ?\)

Which has a higher percentage of nitrogen: carbamazepine, an anticonvulsant, \(\left(\mathrm{C}_{15} \mathrm{H}_{12} \mathrm{~N}_{2} \mathrm{O}\right)\) or carbetapentane, a cough suppressant, \(\left(\mathrm{C}_{20} \mathrm{H}_{31} \mathrm{NO}_{3}\right)\) ?