Chapter 10

Respiration Air contains several gases. When resting, every breath you take contains approximately 0.600 g of air. If argon makes up 0.934% of the air, calculate the number of argon atoms inhaled with each breath.

What information is provided by the formula for potassium chromate \(\left(\mathrm{K}_{2} \mathrm{CrO}_{4}\right) ?\)

In the formula for sodium phosphate \(\left(\mathrm{Na}_{3} \mathrm{PO}_{4}\right),\) how many moles of sodium are represented? How many moles of phosphorus? How many moles of oxygen?

Explain how you determine the molar mass of a compound.

Insect Repellent Many insect repellents use DEET as the active ingredient. DEET was patented in 1946 and is effective against many biting insects. What must you know to determine the molar mass of DEET?

Why can molar mass be used as a conversion factor?

List three conversion factors used in molar conversions.

Which of these contains the most moles of carbon atoms per mole of the compound ascorbic acid \(\left(\mathrm{C}_{6} \mathrm{H}_{8} \mathrm{O}_{6}\right)\) glycerin \(\left(\mathrm{C}_{3} \mathrm{H}_{8} \mathrm{O}_{3}\right),\) or vanillin \(\left(\mathrm{C}_{8} \mathrm{H}_{8} \mathrm{O}_{3}\right) ?\) Explain.

How many moles of oxygen atoms are contained in each compound? a. 2.50 mol of KMnO \(_{4}\) b. 45.9 mol of \(\mathrm{CO}_{2}\) c. \(1.25 \times 10^{-2}\) mol of \(\mathrm{CuSO}_{4} \cdot 5 \mathrm{H}_{2} \mathrm{O}\)

How many carbon tetrachloride \(\left(\mathrm{CCl}_{4}\right)\) molecules are in 3.00 \(\mathrm{mol}\) of \(\mathrm{CCl}_{4} ?\) How many carbon atoms? How many chlorine atoms? How many total atoms?

Determine the molar mass of each compound. a. nitric acid \(\left(\mathrm{HNO}_{3}\right)\) b. ammonium nitrate \(\left(\mathrm{NH}_{4} \mathrm{NO}_{3}\right)\) c. zinc oxide \((\mathrm{ZnO})\) d. cobalt chloride \(\left(\mathrm{CoCl}_{2}\right)\)

Garlic Determine the molar mass of allyl sulfide, the compound responsible for the smell of garlic. The chemical formula of allyl sulfide is \(\left(\mathrm{C}_{3} \mathrm{H}_{5}\right)_{2} \mathrm{S}\) .

How many moles are in 100.0 g of each compound? a. dinitrogen oxide\(\left(\mathrm{N}_{2} \mathrm{O}\right)\) b. methanol \(\left(\mathrm{CH}_{3} \mathrm{OH}\right)\)

What is the mass of each compound? a. \(4.50 \times 10^{-2}\) mol of \(\mathrm{CuCl}_{2}\) b. \(1.25 \times 10^{2} \mathrm{mol}\) of \(\mathrm{Ca}(\mathrm{OH})_{2}\)

Acne Benzoyl peroxide \(\left(\mathrm{C}_{14} \mathrm{H}_{10} \mathrm{O}_{4}\right)\) is a substance used as an acne medicine. What is the mass in grams of \(3.50 \times 10^{-2} \mathrm{mol} \mathrm{C}_{14} \mathrm{H}_{10} \mathrm{O}_{4}\) ?

What is the mass of a mole of electrons if one electron has a mass of \(9.11 \times 10^{-28} \mathrm{g}\) ?

How many moles of ions are in each compound? a. 0.0200 g of AgNO \(_{3}\) b. 0.100 mol of \(\mathrm{K}_{2} \mathrm{CrO}_{4}\) c. 0.500 \(\mathrm{g}\) of \(\mathrm{Ba}(\mathrm{OH})_{2}\) d. \(1.00 \times 10^{-9} \mathrm{mol}\) of \(\mathrm{Na}_{2} \mathrm{CO}_{3}\)

How many formula units are present in 500.0 g of lead(II) chloride?

Calculate the mass of \(3.62 \times 10^{24}\) molecules of glucose \(\left(\mathrm{C}_{6} \mathrm{H}_{12} \mathrm{O}_{6}\right)\)

How many moles of iron can be recovered from 100.0 \(\mathrm{kg}\) of \(\mathrm{Fe}_{3} \mathrm{O}_{4} ?\)

Calculate the moles of aluminum ions present in 250.0 \(\mathrm{g}\) of aluminum oxide \(\left(\mathrm{Al}_{2} \mathrm{O}_{3}\right)\)

Determine the number of chloride ions in 10.75 g of magnesium chloride.

Calculate the number of sodium ions present in 25.0 g of sodium chloride.

Determine the number of oxygen atoms present in 25.0 g of carbon dioxide.

The density of lead (Pb) is 11.3 \(\mathrm{g} / \mathrm{cm}^{3}\) . Calculate the volume of 1 \(\mathrm{mol}\) of \(\mathrm{Pb}\) .

Explain what is meant by percent composition

What information must a chemist obtain in order to determine the empirical formula of an unknown compound?

What information must a chemist have to determine the molecular formula for a compound?

What is the difference between an empirical formula and a molecular formula? Provide an example.

When can the empirical formula be the same as the molecular formula?

Which of the following formulas-NO, \(\mathrm{N}_{2} \mathrm{O}, \mathrm{NO}_{2}, \mathrm{N}_{2} \mathrm{O}_{4}\) and \(\mathrm{N}_{2} \mathrm{O}_{5}-\) represent the empirical and molecular formulas of the same compound? Explain your answer.

Do all pure samples of a given compound have the same percent composition? Explain.

Vitamin \(D_{3}\) Your body's ability to absorb calcium is aided by vitamin \(D_{3} .\) Chemical analysis of vitamin \(D_{3}\) yields the data shown in Figure \(10.22 .\) What$$ \text { Both empirical and molecular formulas for this compound is } C_{27} H_{44} O $$ are the empirical and molecular formulas for vitamin \(D_{3} ?\)

When a 35.07-g sample of phosphorus reacts with oxygen, a 71.00-g sample of phosphorus oxide is formed. What is the percent composition of the compound? What is the empirical formula for this compound?

Cholesterol Heart disease is linked to high blood cholesterol levels. What is the percent composition of the elements in a molecule of cholesterol \(\left(\mathrm{C}_{27} \mathrm{H}_{45} \mathrm{OH}\right)\) ?

Determine the empirical formula for each compound. a. ethylene \(\left(\mathrm{C}_{2} \mathrm{H}_{4}\right)\) b. ascorbic acid \(\left(\mathrm{C}_{6} \mathrm{H}_{8} \mathrm{O}_{6}\right)\) c. naphthalene \(\left(\mathrm{C}_{10} \mathrm{H}_{8}\right)\)

Caffeine The stimulant effect of coffee is due to caffeine, \(\mathrm{C}_{8} \mathrm{H}_{10} \mathrm{N}_{4} \mathrm{O}_{2}\) . Calculate the molar mass of caffeine. Determine its percent composition.

Which titanium-containing mineral, rutile \(\left(\mathrm{TiO}_{2}\right)\) or ilmenite (FeTiO \(_{3} ),\) has the larger percentage of titanium?

Vitamin E Many plants contain vitamin \(\mathrm{E}\left(\mathrm{C}_{29} \mathrm{H}_{50} \mathrm{O}_{2}\right)\) a substance that some think slows the aging process in humans. What is the percent composition of vitamin E?

Artificial Sweetener Determine the percent composition of aspartame \(\left(\mathrm{C}_{14} \mathrm{H}_{18} \mathrm{N}_{2} \mathrm{O}_{5}\right),\) an artificial sweetener.

MSG Monosodium glutamate, known as MSG, is sometimes added to food to enhance flavor. Analysis determined this compound to be 35.5% C, 4.77% H, 8.29% N, 13.6% Na, and 37.9% O. What is its empirical formula?

What is the empirical formula of a compound that contains 10.52 g Ni, 4.38 g C, and 5.10 g N?

Patina The Statue of Liberty has turned green because of the formation of a patina. Two copper compounds, \(\mathrm{Cu}_{3}(\mathrm{OH})_{4} \mathrm{SO}_{4}\) and \(\mathrm{Cu}_{4}(\mathrm{OH})_{6} \mathrm{SO}_{4},\) form this patina. Find the mass percentage of copper in each compound.

What is a hydrated compound? Use an example to illustrate your answer.

Explain how hydrates are named.

Desiccants Why are certain electronic devices transported with desiccants?

In a laboratory setting, how would you determine if a compound was a hydrate?

Write the formula for the following hydrates. a. nickel(II) chloride hexahydrate b. cobalt(II) chloride hexahydrate c. magnesium carbonate pentahydrate d. sodium sulfate decahydrate

Determine the mass percent of anhydrous sodium carbonate \(\left(\mathrm{Na}_{2} \mathrm{CO}_{3}\right)\) and water in sodium carbonate decahydrate \(\left(\mathrm{Na}_{2} \mathrm{CO}_{3} \cdot 10 \mathrm{H}_{2} \mathrm{O}\right)\)

Chromium(III) nitrate forms a hydrate that is 40.50% water by mass. What is its chemical formula?