Chapter 3: Composition of Substances and SolutionsContent check — Chemistry 2e, Chapter 3: Composition of Substances and Solutions

Acetaminophen, C₈H₉NO₂, is a covalent compound and the active ingredient in several popular nonprescription pain medications, such as Tylenol. What is the molecular mass (amu) for this compound?

Calcium phosphate, Ca₃(PO₄)₂, is an ionic compound and a common anti-caking agent added to food products. What is the formula mass (amu) of calcium phosphate?

Beryllium is a light metal used to fabricate transparent X-ray windows for medical imaging instruments. How many moles of Be are in a thin-foil window weighing 3.24 g?

What is the mass of 2.561 mol of gold?

A prospector panning for gold in a river collects 15.00 g of pure gold. How many Au atoms are in this quantity of gold?

How many moles of sucrose, C₁₂H₂₂O₁₁, are in a 25-g sample of sucrose?

What is the mass of 0.443 mol of hydrazine, N₂H₄?

How many C₄H₁₀ molecules are contained in 9.213 g of this compound? How many hydrogen atoms?

A 24.81-g sample of a gaseous compound containing only carbon, oxygen, and chlorine is determined to contain 3.01 g C, 4.00 g O, and 17.81 g Cl. What is this compound’s percent composition?

To three significant digits, what is the mass percentage of iron in the compound Fe₂O₃?

What is the empirical formula of a compound if a sample contains 0.130 g of nitrogen and 0.370 g of oxygen?

What is the empirical formula of a compound containing 40.0% C, 6.71% H, and 53.28% O?

What is the molecular formula of a compound with a percent composition of 49.47% C, 5.201% H, 28.84% N, and 16.48% O, and a molecular mass of 194.2 amu?

A teaspoon of table sugar contains about 0.01 mol sucrose. What is the molarity of sucrose if a teaspoon of sugar has been dissolved in a cup of tea with a volume of 200 mL?

What volume (mL) of the sweetened tea described in Example 3.14 contains the same amount of sugar (mol) as 10 mL of the soft drink in this example?

Calculate the molarity of 6.52 g of CoCl₂ (128.9 g/mol) dissolved in an aqueous solution with a total volume of 75.0 mL.

How many grams of CaCl₂ (110.98 g/mol) are contained in 250.0 mL of a 0.200-M solution of calcium chloride?

What volume of a 1.50-M KBr solution contains 66.0 g KBr?

What is the concentration of the solution that results from diluting 25.0 mL of a 2.04-M solution of CH₃OH to 500.0 mL?

A laboratory experiment calls for 0.125 M HNO₃. What volume of 0.125 M HNO₃ can be prepared from 0.250 L of 1.88 M HNO₃?

What volume of a 0.575-M solution of glucose, C₆H₁₂O₆, can be prepared from 50.00 mL of a 3.00-M glucose solution?

A bottle of a tile cleanser contains 135 g of HCl and 775 g of water. What is the percent by mass of HCl in this cleanser?

What volume of concentrated HCl solution contains 125 g of HCl?

Wine is approximately 12% ethanol (CH₃CH₂OH) by volume. Ethanol has a molar mass of 46.06 g/mol and a density 0.789 g/mL. How many moles of ethanol are present in a 750-mL bottle of wine?

A 50.0-g sample of industrial wastewater was determined to contain 0.48 mg of mercury. Express the mercury concentration of the wastewater in ppm and ppb units.

What is the total mass (amu) of carbon in each of the following molecules?

(a) CH₄

(b) CHCl₃

(c) C₁₂H₁₀O₆

(d) CH₃CH₂CH₂CH₂CH₃

Calculate the molecular or formula mass of each of the following:

(a) P₄

(b) H₂O

(c) Ca(NO₃)₂

(d) CH₃CO₂H (acetic acid)

(e) C₁₂H₂₂O₁₁ (sucrose, cane sugar)

Determine the molecular mass of the following compounds:

(a)

(b)

(c)

(d)

Write a sentence that describes how to determine the number of moles of a compound in a known mass of the compound using its molecular formula.

Which contains the greatest mass of oxygen: 0.75 mol of ethanol (C₂H₅OH), 0.60 mol of formic acid (HCO₂H), or 1.0 mol of water (H₂O)? Explain why.

How are the molecular mass and the molar mass of a compound similar and how are they different?

Calculate the molar mass of each of the following:

(a) S₈

(b) C₅H₁₂

(c) Sc₂(SO₄)₃

(d) CH₃COCH₃ (acetone)

(e) C₆H₁₂O₆ (glucose)

Calculate the molar mass of each of the following:

(a) the anesthetic halothane, C₂HBrClF₃

(b) the herbicide paraquat, C₁₂H₁₄N₂Cl₂

(c) caffeine, C₈H₁₀N₄O₂

(d) urea, CO(NH₂)₂

(e) a typical soap, C₁₇H₃₅CO₂Na

Determine the mass of each of the following:

(a) 0.0146 mol KOH

(b) 10.2 mol ethane, C₂H₆

(c) 1.6 $\times$ 10⁻³ mol Na₂ SO₄

(d) 6.854 $\times$ 10³ mol glucose, C₆ H₁₂ O₆

(e) 2.86 mol Co(NH₃)₆Cl₃

Determine the mass of each of the following:

(a) 2.345 mol LiCl

(b) 0.0872 mol acetylene, C₂H₂

(c) 3.3 $\times$ 10⁻² mol Na₂CO₃

(d) 1.23 $\times$ 10³ mol fructose, C₆H₁₂O₆

(e) 0.5758 mol FeSO₄(H₂O)₇

Determine the mass in grams of each of the following:

(a) 0.600 mol of oxygen atoms

(b) 0.600 mol of oxygen molecules, O₂

(c) 0.600 mol of ozone molecules, O₃

Determine the number of atoms and the mass of zirconium, silicon, and oxygen found in 0.3384 mol of zircon, ZrSiO₄, a semiprecious stone.

Determine which of the following contains the greatest mass of aluminum: 122 g of AlPO₄, 266 g of Al₂Cl₆, or 225 g of Al₂S₃.

The Cullinan diamond was the largest natural diamond ever found (January 25, 1905). It weighed 3104 carats (1 carat = 200 mg). How many carbon atoms were present in the stone?

A certain nut crunch cereal contains 11.0 grams of sugar (sucrose, C₁₂H₂₂O₁₁) per serving size of 60.0 grams. How many servings of this cereal must be eaten to consume 0.0278 moles of sugar?

Which of the following represents the least number of molecules?

(a) 20.0 g of H₂O (18.02 g/mol)

(b) 77.0 g of CH₄ (16.06 g/mol)

(c) 68.0 g of C₃H₆ (42.08 g/mol)

(d) 100.0 g of N₂O (44.02 g/mol)

(e) 84.0 g of HF (20.01 g/mol)

Calculate the following to four significant figures:

(a) the percent composition of ammonia, NH₃

(b) the percent composition of photographic fixer solution (“hypo”), Na₂S₂O₃

(c) the percent of calcium ion in Ca₃(PO₄)₂

Determine the percent ammonia, NH₃, in Co(NH₃)₆Cl₃, to three significant figures.

Determine the empirical formulas for compounds with the following percent compositions:

(a) 15.8% carbon and 84.2% sulfur

(b) 40.0% carbon, 6.7% hydrogen, and 53.3% oxygen

A compound of carbon and hydrogen contains 92.3% C and has a molar mass of 78.1 g/mol. What is its molecular formula?

Determine the empirical and molecular formula for chrysotile asbestos. Chrysotile has the following percent composition: 28.03% Mg, 21.60% Si, 1.16% H, and 49.21% O. The molar mass for chrysotile is 520.8 g/mol.

A major textile dye manufacturer developed a new yellow dye. The dye has a percent composition of 75.95% C, 17.72% N, and 6.33% H by mass with a molar mass of about 240 g/mol. Determine the molecular formula of the dye.

What information is needed to calculate the molarity of a sulfuric acid solution?

Determine the molarity for each of the following solutions:

(a) 0.444 mol of CoCl₂ in 0.654 L of solution

(b) 98.0 g of phosphoric acid, H₃PO₄, in 1.00 L of solution

(c) 0.2074 g of calcium hydroxide, Ca(OH)₂, in 40.00 mL of solution

(d) 10.5 kg of Na₂SO₄·10H₂O in 18.60 L of solution

(e) 7.0 $\times$ 10⁻³ mol of I₂ in 100.0 mL of solution

(f) 1.8 $\times$ 10⁴ mg of HCl in 0.075 L of solution

Consider this question: What is the mass of the solute in 0.500 L of 0.30 M glucose, C₆H₁₂O₆, used for intravenous injection?

(a) Outline the steps necessary to answer the question.

(b) Answer the question.

Calculate the number of moles and the mass of the solute in each of the following solutions:

(a) 2.00 L of 18.5 M H₂SO₄, concentrated sulfuric acid

(b) 100.0 mL of 3.8 $\times$ 10⁻⁶ M NaCN, the minimum lethal concentration of sodium cyanide in blood serum

(c) 5.50 L of 13.3 M H₂CO, the formaldehyde used to “fix” tissue samples

(d) 325 mL of 1.8 $\times$ 10⁻⁶ M FeSO₄, the minimum concentration of iron sulfate detectable by taste in drinking water

Consider this question: What is the molarity of KMnO₄ in a solution of 0.0908 g of KMnO₄ in 0.500 L of solution?

(a) Outline the steps necessary to answer the question.

(b) Answer the question.

Calculate the molarity of each of the following solutions:

(a) 0.195 g of cholesterol, C₂₇H₄₆O, in 0.100 L of serum, the average concentration of cholesterol in human serum

(b) 4.25 g of NH₃ in 0.500 L of solution, the concentration of NH₃ in household ammonia

(c) 1.49 kg of isopropyl alcohol, C₃H₇OH, in 2.50 L of solution, the concentration of isopropyl alcohol in rubbing alcohol

(d) 0.029 g of I₂ in 0.100 L of solution, the solubility of I₂ in water at 20 °C

There is about 1.0 g of calcium, as Ca²⁺, in 1.0 L of milk. What is the molarity of Ca²⁺ in milk?

If 0.1718 L of a 0.3556-M C₃H₇OH solution is diluted to a concentration of 0.1222 M, what is the volume of the resulting solution?

What volume of a 0.33-M C₁₂H₂₂O₁₁ solution can be diluted to prepare 25 mL of a solution with a concentration of 0.025 M?

What is the molarity of the diluted solution when each of the following solutions is diluted to the given final volume?

(a) 1.00 L of a 0.250-M solution of Fe(NO₃)₃ is diluted to a final volume of 2.00 L

(b) 0.5000 L of a 0.1222-M solution of C₃H₇OH is diluted to a final volume of 1.250 L

(c) 2.35 L of a 0.350-M solution of H₃PO₄ is diluted to a final volume of 4.00 L

(d) 22.50 mL of a 0.025-M solution of C₁₂H₂₂O₁₁ is diluted to 100.0 mL

A 2.00-L bottle of a solution of concentrated HCl was purchased for the general chemistry laboratory. The solution contained 868.8 g of HCl. What is the molarity of the solution?

What volume of a 0.20-M K₂SO₄ solution contains 57 g of K₂SO₄?

Consider this question: What mass of a concentrated solution of nitric acid (68.0% HNO₃ by mass) is needed to prepare 400.0 g of a 10.0% solution of HNO₃ by mass?

(a) Outline the steps necessary to answer the question.

(b) Answer the question.

What mass of solid NaOH (97.0% NaOH by mass) is required to prepare 1.00 L of a 10.0% solution of NaOH by mass? The density of the 10.0% solution is 1.109 g/mL.

The hardness of water (hardness count) is usually expressed in parts per million (by mass) of CaCO₃, which is equivalent to milligrams of CaCO₃ per liter of water. What is the molar concentration of Ca²⁺ ions in a water sample with a hardness count of 175 mg CaCO₃/L?

In Canada and the United Kingdom, devices that measure blood glucose levels provide a reading in millimoles per liter. If a measurement of 5.3 mM is observed, what is the concentration of glucose (C₆H₁₂O₆) in mg/dL?

Copper(I) iodide (CuI) is often added to table salt as a dietary source of iodine. How many moles of CuI are contained in 1.00 lb (454 g) of table salt containing 0.0100% CuI by mass?

D5W is a solution used as an intravenous fluid. It is a 5.0% by mass solution of dextrose (C₆H₁₂O₆) in water. If the density of D5W is 1.029 g/mL, calculate the molarity of dextrose in the solution.