This question is about acids and bases found in the laboratory and home.
Propanoic acid, CH3CH2COOH\text{CH}_3\text{CH}_2\text{COOH}CH3CH2COOH, is a weak monoprotic acid.
A student carries out an experiment to determine the pKa\text{p}K_apKa value of CH3CH2COOH\text{CH}_3\text{CH}_2\text{COOH}CH3CH2COOH.
Write the expression for the acid dissociation constant, KaK_aKa, of CH3CH2COOH\text{CH}_3\text{CH}_2\text{COOH}CH3CH2COOH.
Calculate the pKa\text{p}K_apKa value of CH3CH2COOH\text{CH}_3\text{CH}_2\text{COOH}CH3CH2COOH. Give your answer to two decimal places.
Determine the percentage dissociation of propanoic acid in the solution. Give your answer to three significant figures.
Many solid drain cleaners are based on potassium hydroxide, KOH\text{KOH}KOH.
Determine the percentage, by mass, of KOH\text{KOH}KOH in the solid cleaner. Give your answer to three significant figures. [Kw=1.00×10−14 mol2 dm−6K_w = 1.00\times 10^{-14} \text{ mol}^2\text{ dm}^{-6}Kw=1.00×10−14 mol2 dm−6 at 298 K, molar mass of KOH=56.11 g mol−1\text{KOH} = 56.11\text{ g mol}^{-1}KOH=56.11 g mol−1]
Potassium nitrite, KNO2\text{KNO}_2KNO2, is a salt containing the nitrite ion, NO2−\text{NO}_2^-NO2−. The skeletal structure is shown below:
O=N−O− \text{O}=\text{N}-\text{O}^- O=N−O−Draw the 'dot-and-cross' diagram for the nitrite ion. Show outer electrons only and use different symbols for electrons from N and O, and any 'extra' electrons.
