Question

in an experiment, a scientist compares the effect of adding acid rain to samples taken from two different lakes. the scientist observes that ten drops of acid rain added to water taken from lake minnetonka in southern minnesota does not change the ph from 7.5, but ten drops of acid rain added to water taken from upper kintla lake in glacier national park causes the ph to change from 7.5 to 5.2. which conclusion is supported by these observations?

a. neither lake minnetonka nor upper kintla lake contains a buffer.

b. both lake minnetonka and upper kintla lake contain a buffer.

c. upper kintla lake contains a buffer, but lake minnetonka does not.

d. lake minnetonka contains a buffer, but upper kintla lake does not.

Explanation:

A buffer resists pH change. Lake Minnetonka's water (pH 7.5) didn't change with acid rain, so it has a buffer. Upper Kintla Lake's pH changed from 7.5 to 5.2 with acid rain, meaning it lacks an effective buffer (or its buffer capacity was exceeded, but the observation shows significant pH change, so it likely has no buffer or a weak one compared to Minnetonka). So Lake Minnetonka has a buffer, Upper Kintla does not.

Answer:

D. Lake Minnetonka contains a buffer, but Upper Kintla Lake does not.