Understanding HCl + Ca(OH)2 Reaction: pH?

[TylerH]

Homework Statement

I'm trying to understand what happens, chronologically, when 2mol HCl is mixed with 1mol Ca(OH)2 in aqueous solution. Also, is the resulting solution acidic or alkaline.

Homework Equations

$$2HCl + Ca(OH)_2 = 2H^+ + 2Cl^- + Ca^{2+} + 2(OH)^- = ?$$

The Attempt at a Solution

I think the H ion will combine with the OH's to make water, but I don't know what happens to the Cl and Ca ions. If they remain unbonded and just float around in the water, then I don't know what effect this has on pH. They don't donate H, obviously, but they don't covalently bond with it either.

 

[Borek]

You are right - CaCl₂ stays dissociated and doesn't affect pH (well, to some extent it does, but that's most likely not important here). Think just in terms of excess reagent.

 

[AGNuke]

Calcium and Chloride ions are present in aqueous solution (Corrected). Chloride Ions are neutral, so are Calcium ions.

We can also see it as a strong acid HCl reacting with Ca(OH)₂, which is also quite strong, so the resultant salt is quite neutral.

 

[Borek]

Calcium and Chloride Ions are sparingly available as ions themselves, instead, they form insoluble salt, which is precipitated.

Please elaborate, what you wrote doesn't make much sense to me. Calcium chloride is quite soluble, tens of grams in 100 mL of water (even more than NaCl).

 

[DeeNos]

When 2mol of hydrochloric acid (HCl) is mixed with 1mol of calcium hydroxide (Ca(OH)2) in aqueous solution, a neutralization reaction occurs. This reaction can be represented by the equation 2HCl + Ca(OH)2 → 2H2O + CaCl2.

In this reaction, the H+ ions from the HCl combine with the OH- ions from the Ca(OH)2 to form water (H2O), leaving behind the Ca2+ and Cl- ions in solution. The Ca2+ and Cl- ions do not bond with each other, but they do remain in solution and are called spectator ions.

The resulting solution is neutral, with a pH of 7, because the H+ and OH- ions have combined to form water, which is neither acidic nor basic. This is due to the equal concentrations of H+ and OH- ions in the solution, which cancel each other out.

In summary, the reaction between 2mol HCl and 1mol Ca(OH)2 in aqueous solution results in the formation of water and a neutral solution with a pH of 7.