• The acidity of an aqueous solution depends on the number of?H+?ions in solution
• The?pH?is defined as:

pH = -log[H+]

• • where [H+] is the concentration of hydrogen ions in mol dm–3
• Similarly, the?concentration?of?H+?of a solution can be calculated if the pH is known by rearranging the above equation to:

[H+] = 10-pH

• The pH scale is a logarithmic scale with base 10
• This means that each value is 10 times the value below it. For example, pH 5 is 10 times more acidic than pH 6.
• pH values are usually given to 2 decimal places
• The relationship between concentration is easily seen on the following table

pH & [H+] Table

Answer

Answer 1:

The pH of the solution is:

pH? = -log[H+]

= -log 1.6 x 10-4

= 3.80

Answer 2:

The hydrogen concentration can be calculated by rearranging the equation for pH

pH? ?= -log[H+]

[H+] = 10-pH

= 10-3.10

= 7.94 x 10-4?mol dm-3

Answer

The correct option is?C.

• • The total volume after dilution is 1000.0 cm3?so the concentration of H+?has been?reduced?by a factor of 100 or 10-2, which means an increase of 2 pH units
  • The final solution is therefore?pH 3