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Problem 130
Carbon dioxide dissolves in water according to the equations:
CO2(g) + H2O(l) ⇌ H2CO3(aq)
H2CO3(aq) + H2O(l) ⇌ HCO3–(aq) + H3O+(aq)
Carbon dioxide levels in the atmosphere have increased about 20% over the last century. Given that Earth's oceans are exposed to atmospheric carbon dioxide, what effect might the increased CO2 be having on the pH of the world's oceans? What effect might this change be having on the limestone structures (primarily CaCO3) of coral reefs and marine shells?
Problem 131
People often take milk of magnesia to reduce the discomfort associated with acid stomach or heartburn. The recommended dose is 1 teaspoon, which contains 4.00×102 mg of Mg(OH)2. What volume of an HCl solution with a pH of 1.3 can be neutralized by one dose of milk of magnesia? If the stomach contains 2.00×102 mL of pH 1.3 solution, is all the acid neutralized? If not, what fraction is neutralized?
Problem 132
Lakes that have been acidified by acid rain can be neutralized by liming, the addition of limestone (CaCO3). How much limestone (in kg) is required to completely neutralize a 4.3 billion liter lake with a pH of 5.5?
- Acid rain over the Great Lakes has a pH of about 4.5. Calculate the [H3O+] concentration of this rain and compare that value to the [H3O+] concentration of rain over the West Coast, which has a pH of 5.4. How many times more concentrated is the acid in the rain over the Great Lakes compared to the rain over the West Coast?
Problem 133
- White wines tend to be more acidic than red wines. Find the [H3O+] concentration in a Sauvignon Blanc with a pH of 3.23 and a Cabernet Sauvignon with a pH of 3.64. How many times more acidic is the Sauvignon Blanc than the Cabernet Sauvignon?
Problem 134
- Common aspirin is acetylsalicylic acid, which has the structure shown here and a pKa of 3.5. Calculate the pH of a solution in which one normal adult dose of aspirin (6.5 * 10^2 mg) is dissolved in 8.0 ounces of water.
Problem 135
Problem 136
The AIDS drug zalcitabine (also known as ddC) is a weak base with a pKb of 9.8. What percentage of the base is protonated in an aqueous zalcitabine solution containing 565 mg/L?
Problem 137
Determine the pH of each solution. a. 0.0100 M HClO4 b. 0.115 M HClO2 c. 0.045 M Sr(OH)2 d. 0.0852 M KCN e. 0.155 M NH4Cl
Problem 138
Determine the pH of each solution. a. 0.0650 M HNO3 b. 0.150 M HNO2 c. 0.0195 M KOH d. 0.245 M CH3NH3I e. 0.318 M KC6H5O
Problem 139
Determine the pH of each two-component solution. a. 0.0550 M in HI and 0.00850 M in HF b. 0.112 M in NaCl and 0.0953 M in KF c. 0.132 M in NH4Cl and 0.150 M HNO3 d. 0.0887 M in sodium benzoate and 0.225 M in potassium bromide e. 0.0450 M in HCl and 0.0225 M in HNO3
Problem 140d
Determine the pH of each two-component solution. d. 0.088 M HClO4 and 0.022 M KOH
Problem 141
Write net ionic equations for the reactions that take place when aqueous solutions of the following substances are mixed: a. sodium cyanide and nitric acid b. ammonium chloride and sodium hydroxide c. sodium cyanide and ammonium bromide d. potassium hydrogen sulfate and lithium acetate e. sodium hypochlorite and ammonia
Problem 142
Morphine has the formula C17H19NO3. It is a base and accepts one proton per molecule. It is isolated from opium. A 0.682-g sample of opium is found to require 8.92 mL of a 0.0116 M solution of sulfuric acid for neutralization. Assuming that morphine is the only acid or base present in opium, calculate the percent morphine in the sample of opium.
Problem 143
The pH of a 1.00 M solution of urea, a weak organic base, is 7.050. Calculate the Ka of protonated urea.
- What is the concentration of ammonia in a solution prepared by dissolving 0.10 mol of acetic acid and 0.10 mol of ammonium chloride in enough water to make 1.0 L of solution?
Problem 144
Problem 145
Lactic acid is a weak acid found in milk. Its calcium salt is a source of calcium for growing animals. A saturated solution of this salt, which we can represent as Ca(Lact)2, has a [Ca2+] = 0.26 M and a pH = 8.78. Assuming the salt is completely dissociated, calculate the Ka of lactic acid.
- A solution of 0.23 mol of the chloride salt of protonated quinine (QH+), a weak organic base, in 1.0 L of solution has a pH of 4.58. What is the Kb of quinine (Q)?
Problem 146