CAIE A-Level Chemistry A2 25.1.3 Math Definitions Ph Ka Pka and Kw and Use Topic Practice

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Question 1

[Maximum number: 4]

Question (a)

(a)

The KaK_{a} of propanoic acid, CH3CH2COOH\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{COOH}, is 1.35×10−5moldm−31.35 \times 10^{-5} \mathrm{moldm}^{-3} at 298 K.

Solution C is a solution of CH3CH2COOH\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{COOH} with a pH of 3.60 at 298 K.

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Question (i)

(i)

Calculate the concentration of hydroxide ions in solution C.

[OH−]=.............................. mol dm−3\left[\mathrm{OH}^{-}\right]=..............................\ \mathrm{mol\ dm}^{-3}
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Question (ii)

(ii)

Table 3.1 shows three possible values of the KaK_{a} of dimethylpropanoic acid, (CH3)3CCOOH\left(\mathrm{CH}_{3}\right)_{3} \mathrm{CCOOH}.

Place a tick in Table 3.1 to show the correct value. Explain your answer.

Table 3.1

Table 3.1

explanation

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