Question

Acid rain is a dilute solution of acids that dissolve the calcium carbonate in limestone statues. Concentrated acids can dissolve a large piece of limestone in a few days. Statue breakdown due to acid rain can take decades, but statues with intricate carvings break down more quickly. Explain these observations in terms of reaction rates.

Answer 1

Answer:

See the answer below

Explanation:

A weak solution of acid would gradually dissolve the calcium carbonate in limestone statues. For example, dilute sulphuric acid formed from the dissolution of SO2 in rainwater would react with calcium carbonate according to the following equation;

    $H_2SO_4(aq)+CaCO_3(s)-->CaSO_4(s)+CO_2(g)+H_2O (l)$

Generally, the rate of any reaction depends on a host of factors such as temperature, pressure, presence of catalysts, and surface area of reactants. The higher the surface area of reactants, the higher the rate of reaction.

In this case, the rate of reaction of the dilute acid and the calcium carbonate depends on the surface area of the calcium carbonate which happens to be the only solid reactant. Statues with intricate carvings seem to break down more quickly than ordinary statues because they offer more surface area for reaction to take place. The intricate carvings create more surface area for reactions when compared to statues without intricate carvings.