Question

 How many grams of solute is present in 0.4 moles Magnesium hydroxide, Mg(OH)2 in 550 g water, H2O? The molar mass of Mg(OH)2 is 58 g/mol. 

Given: 

Solution:

 How many mL of 0.250 M HCl would react exactly with 30.0 mL of the 0.150 M solution of Ca(OH)2 solution? The chemical reaction involved is: HCl(aq) + NaOH(aq) → NaCl (aq) + H2O (l) 

Given: 

Solution:

Answer 1

Part 1

Number of grams $=0.4×58$

$=23.2g$

Part 2

2HCl $+$ Ca(OH)₂ $\to$ CaCl₂ $+$ 2H₂O

Reacting moles of Ca(OH)₂ $=\frac{30}{1000}×0.150$

$=0.0045$

Moles of HCl $=2×0.0045=0.009$

Volume V

$=\frac{V}{1000}×0.250=0.009$

$V=36ml$