##### Solution Stoichem Questions

label Chemistry
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(a) A sample of solid Ca(OH)2 is stirred in water at 30°C until the solution contains as much dissolved Ca(OH)2 as it can hold. A 100.-mL sample of this solution is withdrawn and titrated with 5.00 ✕ 10−2 M HBr. It requires 48.8 mL of the acid solution for neutralization. What is the molarity of the Ca(OH)2 solution?

(b) What is the solubility of Ca(OH)2 in water, at 30°C, in grams of Ca(OH)2 per 100 mL of solution?

Oct 3rd, 2015

(A):

Ca(OH)2 + 2HBr → CaBr2 + 2H2O
1mol Ca(OH)2 reacts with 2mol HBr

Ma * Va = 2* Mb*Vb
Ma * 100 = 2*0.05* 48.8
Ma = 2*0.05*48.8/100
Ma = 0.0488 mol Ca(OH)2 per litre
Molarity of Ca(OH)2 solution = 0.0488M First answer

Molar mass Ca(OH)2 = 74.093 g/mol
0.0488M = 74.093*0.0488 = 3.616g/litre

(B):

Solubility = 0.3616 g per 100 mL solution.

Please let me know if you need any clarification. I'm always happy to answer your questions. Thank you very much!
Sep 19th, 2015

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Oct 3rd, 2015
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Oct 3rd, 2015
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