Question 13.2: Consider the following solutions at 25°C.a Find the [H^+] an...
Consider the following solutions at 25°C.
a Find the [H^+] and pH of a tap water sample in which [OH^-]= 2.0 \times 10^{-7}.
ANALYSIS
Information given: [OH^-] (2.0 \times 10^{-7}\> M)
Information implied: K_{w} value
Asked for: [H^+] and pH
STRATEGY
1. Substitute into Equation 13.1 to obtain [H^+].
K_{w} = [H^{+}][OH^{-}] (13.1)
2. Substitute into Equation 13.3 to convert [H^+] to pH.
pH = -\log_{10}[H^+] = -\log_{10}[H_{3}O^{+}] (13.3)
b Find the [H^+] and [OH^-] of human blood at pH 7.40.
ANALYSIS
Information given: pH (7.40)
Information implied: K_{w} value
Asked for: [H^+] and [OH^-]
STRATEGY
1. Substitute into Equation 13.3 to convert pH to [H^+].
2. Substitute into Equation 13.1 to obtain [OH^-].
c Find the pOH of a solution in which [H^+] = (5.0)[OH^-].
ANALYSIS
Information given: [H^+] and [OH^-] relation ([H^{+}] = 5.0 [OH^{-}])
Information implied: K_{w} value
Asked for: pOH
STRATEGY
1. Substitute into Equation 13.1 to obtain [OH^-].
2. Substitute into Equation 13.4 to convert [OH^-] to pOH.
