pH and pH Indicators

The pH scale is a range from:

• 1-7
• 0-14
• 1-14
• 1-20

A(n) ______ is a substance with a pH less than 7

• Acid
• Alkaline
• Base
• Buffer

A(n) _______ is a substance with a pH greater than 7.

• Base
• Acid
• Buffer
• Water

A solution with a pH of 8.6 would be...

• Acid
• Base
• Neutral
• Acid and Base

What does pH measure?

• the amount of hydrogen (H⁺) ions

• the amount of hydroxide (OH^-) ions

• amount of water

• all of the above

As one moves down the pH scale from 14 to 1, what happens to the concentration of H+ in the solution?

• concentration of H+ decreases

• concentration of H+ increases

• concentration of H+ stays the same

Answer explanation

Since Acids produce H+ ions, the more acidic a substance is, the more H+ ions are created. Substances get more acidic as their pH approached zero.

Which of the following pH values represent the highest concentration of hydronium ions?

• 8

• 4

• 14

• 2

For every power of 10 in concentration of hydronium ions, the pH will change how much?

A solution with a pH of 3 is 1,000 times more acidic than a solution with a pH of

Answer explanation

Each number on the pH scale is separated by a factor of ten. This means that a pH of 1 is 10 times more concentrated than a pH of 2 (and 2 is 10 times less concentrated). A difference of 1000 is equal to 10x10x10, or 3 numbers on the pH scale. Since the question is stating that 3 is more acidic, that means we need to move to a higher number on the pH scale (towards 14). Three numbers higher than a pH of 3 is a pH of 6.

A solution with a pH of 8 is 100 times less basic than a solution with a pH of

Answer explanation

Each number on the pH scale is separated by a factor of ten. This means that a pH of 1 is 10 times more concentrated than a pH of 2 (and 2 is 10 times less concentrated). A difference of 100 is equal to 10x10, or 2 numbers on the pH scale. Since the question is stating that 8 is less basic, we need to move to a higher number on the pH scale (towards 14). Two numbers higher than a pH of 8 is a pH of 10.