When $\text{CH}_3\text{CHClCOOH}$ is placed in water, an equilibrium is established. Write the equation for this equilibrium.
A solution of pH 1.51 is made by dissolving 0.150 mol of $\text{CH}_3\text{CHClCOOH}$ in $250\,\text{cm}^3$ of distilled water. Calculate the $pK_a$ of $\text{CH}_3\text{CHClCOOH}$.
Propanoic acid in aqueous solution has pH 2.55 when its concentration is the same. Explain why the pH values of equally concentrated $\text{CH}_3\text{CHClCOOH}$ and propanoic acid solutions are different.
Alanine is an amino acid. Its isoelectric point is 6.1. State what is meant by isoelectric point.
Give the structural formula of alanine at $\text{pH} = 2$.
Alanine occurs as two optical isomers. Fig. 5.2 shows one of them. Draw the three-dimensional structure of the other optical isomer of alanine.
Polymer $C$ is produced by reacting alanine with 4-aminobutanoic acid, $\text{H}_2\text{N(CH}_2)_3\text{COOH}$. Draw a repeat unit of $C$. The functional group formed should be shown.
State the type of polymerisation shown in (b)(iv).
Scientists are considering $C$ as a substitute for poly(propene) in packaging. Suggest one advantage of using $C$ instead of poly(propene).
A student examines the reaction of $\text{CH}_3\text{CHClCOOH}$ with aqueous $\text{NH}_3$ to work out the reaction mechanism. Reaction 1 is $\text{CH}_3\text{CHClCOOH} + \text{NH}_3 \rightarrow \text{CH}_3\text{CHClCOO}^- + \text{NH}_4^+$. Identify the conjugate acid-base pairs in reaction 1.
Use Fig. 5.3 to demonstrate that reaction 2 is first order with respect to $[\text{CH}_3\text{CHClCOO}^-]$.
Explain why a large excess of $\text{NH}_3$ must be used to obtain the results in Fig. 5.3.
The student measures how changing the concentration of $\text{NH}_3$ affects the rate of reaction 2. Table 5.1 contains the results. Use the information in Table 5.1 and in (c)(ii) to decide whether the nucleophilic substitution reaction follows an $S_N1$ or an $S_N2$ mechanism. Explain your answer.
Describe the effect of an increase in temperature on the rate of reaction of $\text{CH}_3\text{CHClCOO}^-$ and $\text{NH}_3$. Explain your answer.
When an excess of $\text{CH}_3\text{CHClCOO}^-$ is used, further substitution reactions take place. One product has the formula $\text{C}_6\text{H}_9\text{NO}_4^{2-}$. Suggest the structure of $\text{C}_6\text{H}_9\text{NO}_4^{2-}$.