Question

In an experiment, the molecular formula for calcium hydroxide was determined to be Ca(OH)₂. In this experiment, 0.55 g of Ca (s) was added to 150 mL of DI water. After add- ing 10 drops of 0.1% thymol blue indicator, the solution was titrated with 0.30 M HCl.

a) Write the balanced equation for the net ionic reaction that occurred during the titration.

Answer 1

The net ionic equation for the titration of Ca(OH)2 with HCl is Ca(OH)2 (s) + 2H+ (aq) → Ca2+ (aq) + 2H2O (l), after cancelling the Cl- spectator ions.

Step-by-step explanation:

The net ionic equation for the titration of calcium hydroxide, Ca(OH)2, with hydrochloric acid, HCl, is:

Ca(OH)2 (s) + 2HCl (aq) → CaCl2(aq) + 2H2O (l)

To write the net ionic equation:

1. Start with the molecular equation and separate the compounds that are strong electrolytes into ions.
2. Cancel out the spectator ions that appear on both sides of the equation.
3. Write the remaining ions and molecules to form the net ionic equation.

In this case, since calcium hydroxide is a strong base and HCl is a strong acid, they both dissociate fully in water. However, Ca(OH)2 is insoluble and its solid form should not be dissociated in the equation.

Net ionic equation:

Ca(OH)2 (s) + 2H+ (aq) + 2Cl− (aq) → Ca2+ (aq) + 2Cl− (aq) + 2H2O (l)

After cancelling the spectator ions (Cl−), we get:

Ca(OH)2 (s) + 2H+ (aq) → Ca2+ (aq) + 2H2O (l)