IMAT 2015 Q52 [pH]

Which one of the following 0.01 M aqueous solutions has a pH > 7.0?

A. AlBr_3
B. NaI
C. NH_4Cl
D. Na_2CO_3
E. CH_3CO_2H

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First, ethanoic acid will be acidic when dissolved in water. It reacts with water to produce hydroxonium ions and ethanoate ions, but the back reaction is more successful than the forward one. The ions react very easily to reform the acid and the water. Sp, we can eliminate E.

Next, we know that halides dissolved in water do not produce basic solutions. Halogens react to a small extent with water, forming acidic solutions with bleaching properties . We can eliminate A, B and C.

When dissolved in water, sodium carbonate forms carbonic acid and sodium hydroxide, sodium hydroxide is known as the strong base, so it neutralizes acidic gastric pH thereby acting as an antacid. Our answer is therefore D.