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Problem 8
Write a balanced equation for the proton transfer reaction between hydrofluoric acid (HF) and ammonia (NH3). Identify each conjugate acid-base pair, and rewrite the equilibrium arrows to indicate if the forward or reverse reaction is favored.
Problem 9
From this electrostatic potential map of the amino acid alanine, identify the most acidic hydrogens in the molecule:
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Problem 23
Show how ethylamine (C2H5NH2) reacts with hydrochloric acid to form an ethylammonium salt.
Problem 34
Electrostatic potential maps of acetic acid (CH3CO2H) and ethyl alcohol (CH3CH2OH) are shown. Identify the most acidic hydrogen in each, and tell which of the two is likely to be the stronger acid.
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Problem 38
What happens when a strong acid such as HBr is dissolved in water?
Problem 39
What happens when a weak acid such as CH3CO2H is dissolved in water?
Problem 40
What happens when a strong base such as KOH is dissolved in water?
Problem 41
What happens when a weak base such as NH3 is dissolved in water?
Problem 42
What is the difference between a monoprotic acid and a diprotic acid? Give an example of each.
Problem 43
What is the difference between H+ and H3O+?
Problem 51
How is Kw defined, and what is its numerical value at 25 °C?
Problem 71
Rearrange the equation you wrote in Problem 10.50 to solve for [H3O+] in terms of Ka.
Problem 76a
The pH of a buffer solution containing 0.10 M acetic acid and 0.10 M sodium acetate is 4.74.
a. Write the Henderson–Hasselbalch equation for this buffer.
Problem 83
How does normality compare to molarity for monoprotic and polyprotic acids?
Problem 84b
Identify the number of equivalents per mole for each of the following acids and bases.
b. H3PO4
Problem 88a
How many equivalents of an acid or base are in the following?
a. 0.25 mol Mg(OH)2
Problem 90
What are the molarity and the normality of a solution made by dissolving 5.0 g of Ca(OH)2 in enough water to make 500.0 mL of solution?
Problem 91
What are the molarity and the normality of a solution made by dissolving 25 g of citric acid (triprotic, C6H5O7H3) in enough water to make 800 mL of solution?
Problem 98a
A solution is prepared by bubbling 15.0 L of HCl(g) at 25 °C and 1 atm into 250.0 mL of water.
a. Assuming all the HCl dissolves in the water, how many moles of HCl are in solution?
Problem 99b
The dissociation of water into H3O+ and OH– ions depends on temperature. At 0 °C the [H3O+] = 3.38 x 10–8 M, at 25 °C the [H3O+] = 1.00 x 10–7 M, and at 50 °C the [H3O+] = 2.34 x 10–7 M.
b. What is the value of Kw at 0 °C and 50 °C?
Problem 99c
The dissociation of water into H3O+ and OH– ions depends on temperature. At 0 °C the [H3O+] = 3.38 x 10–8 M, at 25 °C the [H3O+] = 1.00 x 10–7 M, and at 50 °C the [H3O+] = 2.34 x 10–7 M.
c. Is the dissociation of water endothermic or exothermic?
Problem 103a
One of the buffer systems used to control the pH of blood involves the equilibrium between H2PO4– and H2PO42–. The pKa for H2PO42– is 7.21.
a. Write the Henderson-Hasselbalch equation for this buffer system.
Problem 109b
Obtain a package of Alka-Seltzer, an antacid, from the local drug store:
b. Why does Alka-Seltzer foam and bubble when dissolved in water? Which ingredient is the antacid?
- Research the composition of 'smelling salts'—a product that is used to rouse people who have lost consciousness. What are the chemical reactions that generate the 'active' component?
Problem 110
Problem 111a
Many allergy medications contain antihistamines, compounds that contain amine groups (R-NH2, where R refers to an organic functional group). Would you expect these compounds to be acidic, basic or neutral? Explain.
a. One over-the-counter product lists the active ingredient as "diphenhydramine HCl." What does this designation mean?