Exercises

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)

Calculate the following to four significant figures:

(a) the percent composition of ammonia, NH₃

(b) the percent composition of photographic “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 do we need 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 $\times$ 10⁻⁵ 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.