A $0.036 M$ aqueous nitrous acid $\left(\mathrm{HNO}_2\right)$ solution has an osmotic pressure of $0.93 \mathrm{~atm}$ at $25^{\circ} \mathrm{C}$. Calculate the percent ionization of the acid.

Hyaluronic acid acts as a lubricant in the synovial fluid of joints. In rheumatoid arthritis, inflammation breaks down hyaluronic acid to smaller molecules. Under these conditions, what happens to the lubricating power of the synovial fluid?

A typical vitamin C tablet (containing pure ascorbic acid, $\mathrm { H } _ { 2 } \mathrm { C } _ { 6 } \mathrm { H } _ { 6 } \mathrm { O } _ { 6 } )$ weighs 500. mg. One vitamin C tablet is dissolved in enough water to make 200.0 ml of solution. Calculate the pH of this solution. Ascorbic acid is a diprotic acid.

The value cited for $\mathrm{K}_{1}$ of carbonic acid, $4.3 \times 10^{-7}$, is determined by measuring the pH of water to which a known amount of carbon dioxide has been added. When we recall that only 0.3% of carbon dioxide is converted to carbonic acid in water, what is the "true $\mathrm{K}_{1}$" of carbonic acid?

A dilute aqueous solution of boric acid, $\mathrm{H}_3 \mathrm{BO}_3$, is often used as an eyewash. How would you prepare 500.0 mL of a 0.50%(m/v) boric acid solution?

Which of the following molecules will produce the most ATP per mole?

a. glucose or maltose

b. myristic acid, $\mathrm{CH}_3-\left(\mathrm{CH}_2\right)_{12}-\mathrm{COOH}$, or stearic acid, $\mathrm{CH}_3-\left(\mathrm{CH}_2\right)_{16}-\mathrm{COOH}$

c. glucose or two acetyl CoAs

d. glucose or caprylic acid $\left(\mathrm{C}_8\right)$

e. citrate or succinate in one turn of the citric acid cycle

Common Reaction Steps in the Fatty Acid Oxidation Cycle and Citric Acid Cycle

Cells often use the same enzyme reaction pattern for analogous metabolic conversions. For example, the steps in the oxidation of pyruvate to acetyl $\mathrm{CoA}$ and of $\alpha$-ketoglutarate to succinyl-CoA, although catalyzed by different enzymes, are very similar. The first stage of fatty acid oxidation follows a reaction sequence closely resembling a sequence in the citric acid cycle. Use equations to show the analogous reaction sequences in the two pathways.

A $0.036$- $M$ aqueous nitrous acid $\left(\mathrm{HNO}_2\right)$ solution has an osmotic pressure of $0.93 \mathrm{~atm}$ at $25^{\circ} \mathrm{C}$. Calculate the percent ionization of the acid.

Which is the stronger acid, $\mathrm{H}_{2} \mathrm{SO}_{4}$ or $\mathrm{H}_{2} \mathrm{SeO}_{4}$? Why? You may wish to review the chapter on acid-base equilibria.

How many moles of hydrofluoric acid, $HF$, must be added to 500.0 mL of 0.25 $M$ sodium fluoride to give a buffer of pH 3.50? Ignore the volume change due to the addition of hydrofluoric acid.

A physician wishes to prepare a buffer solution at pH = 3.82 that efficiently resists changes in pH yet contains only small concentrations of the buffering agents. Determine which one of the following weak acids, together with its sodium salt, would probably be best to use: m-chlorobenzoic acid, Ka = 1.04×10^- 4; p-chlorocinnamic acid, Ka = 3.89×10^-5; 2,5-dihydroxybenzoic acid, Ka = 1.08×10^-3; or acetoacetic acid, Ka = 2.62×10^-4. Explain.

In the titration of a weak acid and strong base, the pH is given by $c+\ln \frac{x}{1-x}$, where f is the fraction (0<x<1) of converted acid. What happens to the rate of change of pH as x approaches 1?

How to draw a Lewis structure of HN${_3}$ (hydrazoic acid)?

In the context of fatty acid oxidation to acetyl CoA, indicate whether each of the following substances is involved in (1) fatty acid activation (2) fatty acid transport or (3) $\beta$-oxidation pathway. More than one choice may be correct in a given situation.

a. acyl carnitine

b. enoyl CoA

c. CoA

d. $\text{NAD}^+$