Answer
(a) $pH = 7.00$
(b) $pH > 7.00$
(c) $pH < 7.00$
(d) $pH > 7.00$
Work Step by Step
1. Identify which compound is stronger; the solution will have its characteristics:
(b) $Ba(OH)_2$ Strong base, $HOI$ Weak acid.
The base is the stronger one: Basic solution, $pH > 7$
(c) $HBr$ Strong acid, $C_6H_5NH_2$ Weak base.
The acid is the stronger one: Acidic solution, $pH < 7$
(d) $HNO_2$ Weak acid, $KOH$ Strong base.
The base is the stronger one: Basic solution, $pH > 7$
2. When we have 2 strong compounds, the solution will be neutral, because they are going to completely neutralize each other.
(a) $HNO_3$ Strong acid, $KOH$ Strong base.
Both have the same strength: Neutral solution, $pH = 7$
Why does that happen?
When we mix, for example: $Ba(OH)_2$ and $HOI$, this is the reaction:
$Ba(OH)_2(aq) + HOI(aq) -- \gt Ba^{2+}(aq) + OI^-(aq) + H_2O(l)$
Now, let's analyze each product:
$Ba^{2+}$: No significant acidity/basicity;
$OI^-$: Weak base;
Since we only have a base acting in the solution, it will be a basic one.
When we have a strong acid and a strong base:
$HNO_3(aq) + KOH(aq) -- \gt H_2O(l) + K^+(aq) + NO{_3}^-(aq)$
$K^+$: No significant acidity/basicity;
$N{O_3}^-$: No significant acidity/basicity;
Therefore, the solution will be neutral.
