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Grade 11 Chemistry Effective Homework 6: Comparing Ion Concentrations | Brief Solutions
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1 Ion-concentration order in $0.1$ mol/L ammonium sulfate. Show answer
2 Relation between hydroxide and other species in Na2S solution. Show answer
3 Choose correct concentration relations during acetic-acid neutralization by NaOH. Show answer
4 Choose the concentration relation that must hold. Show answer
5 An acidic solution contains only NH4+, Cl-, H+ and OH-. Choose incorrect statements. Show answer
6 Equal volumes of equimolar acetic acid and sodium acetate are mixed. Choose correct relations. Show answer
7 NaClO conservation, hydrolysis and reaction with SO2: choose incorrect statements. Show answer
8 pH curves for adding HCl or NaOH to NaHCO3: choose correct statements. Show answer
9 Compare alkalinity, ion counts and material balances for equal-volume equimolar NaClO2 and NaClO. Show answer
10 Nitrogen and carbon species distributions while adding ammonia to carbonic acid: choose incorrect statements. Show answer
11.1 Which equimolar solution has higher pH: Na2SeO3 or Na2CO3? Show answer
11.2 Which equimolar solution has greater water ionization: NaHSeO3 or NaHCO3? Show answer
11.3a Write the charge balance for NaHSeO3. Show answer
$c(\mathrm{Na^+})+c(\mathrm H^+)=c(\mathrm{HSeO_3^-})+2c(\mathrm{SeO_3^{2-}})+c(\mathrm{OH^-})$
11.3b Write the material balance for $0.01$ mol/L NaHSeO3. Show answer
$c(\mathrm{Na^+})=c(\mathrm{H_2SeO_3})+c(\mathrm{HSeO_3^-})+c(\mathrm{SeO_3^{2-}})=0.01\ \mathrm{mol\,L^{-1}}$
11.3c Write the proton balance for NaHSeO3. Show answer
$c(\mathrm H^+)+c(\mathrm{H_2SeO_3})=c(\mathrm{OH^-})+c(\mathrm{SeO_3^{2-}})$
11.3d At pH $4.59$, find $[\mathrm{H_2SeO_3}]/[\mathrm{HSeO_3^-}]$. Show answer
11.4 Na2CO3 absorbs a small amount of H2SeO3. Write the ionic equation and find $K$. Show answer
$\mathrm{2CO_3^{2-}+H_2SeO_3\rightleftharpoons2HCO_3^-+SeO_3^{2-}}$;$K\approx2.93\times10^{11}$
12.1 Equal sample halves release $0.04$ mol SO2 and $0.05$ mol NH3. Find the ammonium-sulfite to ammonium-hydrogen-sulfite mole ratio. Show answer
12.2 Choose correct material and charge balances in NH4HSO3. Show answer
12.3 Why is ammonium-sulfite solution alkaline? Show answer
The basic effect of sulfite hydrolysis exceeds the acidic effect of ammonium hydrolysis, so $c(\mathrm{OH^-})>c(\mathrm H^+)$.
12.4 Write the reaction explaining the falling sulfite-to-hydrogen-sulfite ratio during SO2 absorption. Show answer
$\mathrm{(NH_4)_2SO_3+SO_2+H_2O\to2NH_4HSO_3}$
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