Answer:
a. pH raises
b. pH neutral
c. pH raises
Explanation:
First of all we need to dissociate these compounds.
Ca(OH)₂ → Ca²⁺ + 2OH⁻
This is the calcium hydroxide, a strong base.
In this case, we are giving OH⁻ to medium, so the pH will be increased.
OH⁻ + H⁺ ⇄ H₂O
Hydroxides will neutralize the protons in order to make water, but if we have many OH, we talk about a basic solution where pH is lower than 7.
b. CuBr → Cu⁺ + Br⁻
This is similar to NaCl, a ionic salt which is neutral.
The ions from this salt, do not make hydrolisis, that's why pH does not change.
c. Ca₃(PO₄)₂ → 3Ca²⁺ + 2PO₄⁻³
Calcium cathion comes from a strong base. It means, that the ion can not make hydrolisis because it is the conjugate weak acid.
Phosphate anion comes from a weak acid, it can gives OH⁻ to medium so pH will increase; the PO₄⁻³ anion is the conjugate strong base of the phosphoric acid, that's why it can react:
PO₄⁻³ + H₂O ⇄ H₂PO⁻² + OH⁻
