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LOGARITHMS, ANTI-LOGARITHMS, AND pH
Practice Problems
Self-Test Answer Key:
Please complete the following:
1. What is the pH of a solution with a hydrogen ion concentration of
0.001 M?
pH = -log [0.001] = -(-3) = 3
2. What is the pH of a solution with a hydrogen ion concentration of
0.003 M?
pH = -log [0.003] = -(-2.5) = 2.5
3. What is the pH of a solution with a hydrogen ion concentration of 2 X
10-1 M?
pH = -log [2 X 10-1] = -(-0.7) = 0.7
4. What is the hydrogen ion concentration of a solution with a pH of 2?
[H+] = antilog -2 = 10-2 = 0.01 M
5. What is the hydrogen ion concentration of a solution with a pH of 3?
[H+] = antilog -3 = 10-3 = 0.001 M
6. What is the hydrogen ion concentration of a solution with a pH of 2.5?
[H+] = antilog -2.5 = 10-2.5 = 0.003M
Complete the following:
1. log 3 = _____0.48_______
2. log 10 = ____1_____
3. log 0.1 = ______-1_____
4. antilog 2 = ____100____
5. antilog 3 = ______1000____
2
6. antilog 2.5 = ____316_______
Without using a calculator, explain how you know that the following is
incorrect.
1. log 50 = 3.2
log 10 < log 50 < log 100
Therefore:
1 < log50 < 2
But 3.2 is NOT between 1 and 2, so this answer must be incorrect.
2. antilog 4.5 = 123,456
antilog 4 < antilog 4.5 < antilog 5
Therefore:
10,000 < antilog 4.5 < 100,000
But 123,456 is NOT between 10,000 and 100,000, so this answer must be
incorrect.