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Grade 11 Chemistry Effective Homework 3: Ionization of Water and Acidity and Alkalinity of Solutions | Brief Solutions
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1 Which instrument can measure pH as $6.25$? Show answer
2 Which property is larger for pure water at $20^\circ\mathrm C$ than at $60^\circ\mathrm C$? Show answer
3 Choose the solution that must be neutral. Show answer
4 Choose incorrect statements from $K_w$ values at $25$ and $35^\circ\mathrm C$. Show answer
5 Compare acidity of the four specified solutions at room temperature. Show answer
6 Which pairs of solution pH values can give neutrality at a suitable mixing ratio? Show answer
7 Add dilute sulfuric acid to barium hydroxide: choose the incorrect statement. Show answer
8 Add sodium hydrogen sulfate to water at fixed temperature: choose the correct statement. Show answer
9 Water-derived hydrogen-ion concentration is $10^{-12}$ mol/L. Choose correct statements. Show answer
10 pH, paper precision and hydroxide concentrations in different HCl solutions. Show answer
11 For $AG=\lg(c(\mathrm H^+)/c(\mathrm{OH^-}))$, choose correct statements. Show answer
12 Heavy-water ion product $1.6\times10^{-13}$: choose correct pD calculations. Show answer
13 Sulfuric acid of pH $1$ fully precipitates barium nitrate and gives pH $2$. Find the acid-to-original-solution volume ratio. Show answer
14.1 Write acetic-acid ionization. Show answer
$\mathrm{CH_3COOH\rightleftharpoons H^++CH_3COO^-}$
14.2 Write aqueous-ammonia ionization. Show answer
$\mathrm{NH_3\cdot H_2O\rightleftharpoons NH_4^++OH^-}$
14.3 Write stepwise carbonic-acid ionization. Show answer
$\mathrm{H_2CO_3\rightleftharpoons H^++HCO_3^-}$;$\mathrm{HCO_3^-\rightleftharpoons H^++CO_3^{2-}}$
14.4 Write barium-hydroxide dissociation. Show answer
$\mathrm{Ba(OH)_2\to Ba^{2+}+2OH^-}$
14.5 Write copper(II)-hydroxide ionization equilibrium. Show answer
$\mathrm{Cu(OH)_2\rightleftharpoons Cu^{2+}+2OH^-}$
14.6 Write sodium hydrogen sulfite dissociation in water. Show answer
$\mathrm{NaHSO_3\to Na^++HSO_3^-}$;$\mathrm{HSO_3^-\rightleftharpoons H^++SO_3^{2-}}$
15.1 Write liquid-ammonia autoprotolysis by analogy with water. Show answer
$\mathrm{2NH_3\rightleftharpoons NH_4^++NH_2^-}$
15.2 Write pure hydrogen-peroxide autoprotolysis. Show answer
$\mathrm{2H_2O_2\rightleftharpoons H_3O_2^++HO_2^-}$
16.1 Room-temperature pH $0$: find hydrogen-ion concentration. Show answer
$1\ \mathrm{mol\,L^{-1}}$
16.2 Room-temperature pH $4$: find hydroxide concentration. Show answer
$10^{-10}\ \mathrm{mol\,L^{-1}}$
16.3 pH of $0.05$ mol/L sulfuric acid under the school-level complete-dissociation model. Show answer
16.4 Find the concentration of barium hydroxide at pH $13$. Show answer
$0.05\ \mathrm{mol\,L^{-1}}$
16.5 Mix HCl and sulfuric acid, both at pH $2$, in a $3:1$ volume ratio. Find pH. Show answer
16.6 Dissolve $0.23$ g sodium in water and make $100$ mL. Find pH. Show answer
17.1 In NaOH titration of ammonium hydrogen sulfate, which point has the greatest water ionization? Show answer
17.2 Conductivity trend during that titration. Show answer
18.1 At W, $c(\mathrm H^+)=c(\mathrm{OH^-})=10^{-6}$. Find $K_w$. Show answer
18.2 Compare $T$ with $25^\circ\mathrm C$ and explain. Show answer
A, $T>25^\circ\mathrm C$. Water ionization is endothermic, so $K_w$ rises with temperature.
18.3 At $25^\circ\mathrm C$, can adding sulfuric acid leave water at neutral point N? Show answer
No. Sulfuric acid supplies hydrogen ions, giving $c(\mathrm H^+)>c(\mathrm{OH^-})$.
18.4 Which solutes move N to acidic point P? Show answer
18.5 How can N move to neutral point Q at a higher temperature? Show answer
18.6 At $T$, water-derived hydrogen ions in sulfuric acid are $10^{-8}$ mol/L. Find pH and methyl-orange color. Show answer
18.7 At $T$, mix NaOH solutions of pH $12$ and $10$ in a $2:3$ volume ratio. Find pH. Show answer
18.8 At a certain temperature, $0.01$ mol/L NaOH has pH $11$. Find $K_w$. Show answer
18.8a At that temperature, NaOH of pH $a$ and sulfuric acid of pH $b$ mix neutrally in a $10:1$ volume ratio. Find $a+b$. Show answer
18.8b At the same temperature, NaOH of pH $12$ and sulfuric acid of pH $2$ give pH $10$. Find the base-to-acid volume ratio. Show answer
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