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Question

The water in some lakes is basic because the rock underneath the lake is limestone rock made up of calcium carbonate. What chemical reaction happens when acid rain falls on a lake such as this? What happens to the lake's pH?

Answer 1

I'll put charges in brackets like this: (+) because otherwise the equation gets too confusing:

2 H(+) + CO3 (2-) --> H2O + CO2

The lake's pH decreases since it is becoming less basic.