Compare the acidities of 2-chloropropanoic acid, 3-chloropropanoic acid, and propanoic acid, and explain your reasoning. Give the sequence from the most acidic to the least acidic.
The $K_a$ values for methanoic acid, $\text{HCO}_2\text{H}$, and pyruvic acid, $\text{CH}_3\text{COCO}_2\text{H}$, are provided. An equilibrium mixture containing the two acid-base pairs is established: $\text{HCO}_2^- + \text{CH}_3\text{COCO}_2\text{H} \rightleftharpoons \text{HCO}_2\text{H} + \text{CH}_3\text{COCO}_2^-$. Use the $K_a$ values to calculate the equilibrium constant, $K_{eq}$, for this equilibrium.
Use your value of $K_{eq}$ to predict the position of this equilibrium. Show this by putting a tick ($\checkmark$) in the correct box in the table. Explain your answer.
Ethanedioic acid, $\text{HO}_2\text{CCO}_2\text{H}$, has two dissociation constants, $K_{a1}$ and $K_{a2}$, whose $pK_a$ values are 1.23 and 4.19. Suggest equations to show the two dissociations that produce these $pK_a$ values.
State the mathematical relationship between $pK_a$ and the acid dissociation constant $K_a$.
Three tests were performed on separate samples of the organic acids shown in the table. The results are given below. $\checkmark$ = observed change, $\times$ = no observed reaction. Complete the table with the reagent(s) and conditions and the observed change for each test. Assume these organic acids all have a similar acid strength.
Ethanedioic acid, $\text{HO}_2\text{CCO}_2\text{H}$, has two dissociation constants, $K_{a1}$ and $K_{a2}$, whose $pK_a$ values are $1.23$ and $4.19$. Suggest equations to show the two dissociations that give rise to these $pK_a$ values. $pK_{a1} = 1.23$ $pK_{a2} = 4.19$
State the mathematical relationship between $pK_a$ and the acid dissociation constant $K_a$.
A sample of pyruvic acid, $\text{CH}_3\text{COCO}_2\text{H}$, is studied by carbon-13 NMR spectroscopy. Three peaks are seen. Complete the table by: • circling the carbon atom responsible for the chemical shift • stating the hybridisation of the circled carbon atom.
An ester of pyruvic acid, $F$, is dissolved in $\text{CDCl}_3$ and examined by proton NMR spectroscopy. The proton NMR spectrum of $F$ is shown. Use the proton NMR spectrum of $F$ to complete the table.
Deuterium oxide, $\text{D}_2\text{O}$, where D is $^{2}_{1}\text{H}$, can be used as a solvent in proton NMR spectroscopy. The proton NMR spectrum of alanine in $\text{CDCl}_3$ has 4 peaks. The proton NMR spectrum of alanine in $\text{D}_2\text{O}$ has 2 peaks. On the diagram of alanine, circle the protons that show peaks in both NMR spectra. Explain your answer.
The ionic product, $K_w$, for $\text{D}_2\text{O}$ has a value of $1.35 \times 10^{-15}\,\text{mol}^2\text{dm}^{-6}$ at $298\,\text{K}$. Write the expression for the $K_w$ of $\text{D}_2\text{O}$.
Calculate the pH of pure, neutral $\text{D}_2\text{O}$ at $298\,\text{K}$. Assume $[\text{D}^+]$ is equivalent to $[\text{H}^+]$ for pH calculations.