Question

150 ml of $C_2{H}_{5}OH$ (density = 0.78 gm/ml) is diluted to one liter by adding water, molarity of the solution is:

• A. 2.54
• B. 11.7
• C. 2.99
• D. 29.9

Answer 1

Answer: (A)

2.54

Density $=\frac{Mass}{Volume}$

$\therefore$ Mass of ethanol $=$ Density $\times$ Volume

$=0.78\times 150$

$=117g$

$n=\frac{117}{46}=2.54$ moles

Molarity $=\frac{2.54}{1}=2.54M$

$[asMolarity=\frac{molesofsolute}{totalvolumeinlitre}]$