Question

The hcl used in the laboratory is 21.3%(w/v).what is molarity

Answer 1

Final Answer : 5.82M

Steps and Understanding:
1) % Weight by Volume
= Weight of Solute ( in g) / Volume of Solution ( in mL)

2) 21.3% (w/V ) means 21.3g of HCl is dissolved in 100mL solution.
Molar Mass of HCl = 36.6g
No of moles of HCl = 21.3 / 36.6
Volume of Solution = 100mL = 0.1L

3)
Now,
Molarity = No. of moles of solute / Volume of Solution (in L)


$= \frac{ \frac{21.3}{36.6} }{0.1 \: litre} \\ = 5.82molar$

Therefore,Molarity of HCl is 5.82 M.

Answer 2

The molarity of HCl is 5.81 M

Given:

21.3 gm of hydrochloric acid is dissolved in 100 ml of water.

To find:

The molarity of HCL

Solution:

From the given,

HCl is 21.3 $\frac {w}{v}$ means 21.3 gm of hydrochloric acid is dissolved in 100 ml of water.

Therefore, mass of HCl = 21.3 gm

Molar mass of HCl = 36.6 gm

$Number \quad of \quad moles \quad of \quad HCl=\frac {\text {Given mass}}{\text {Molar mass}}$

$= \frac {(21.3\text{ gm})}{(36.6 \text \frac {g}{mol})}= 0.581 m$

$Molarity \quad of \quad HCl= \frac {\text (Number \quad of \quad moles \quad of \qaud HCl)}{ \text (Volume \quad of \quad HCl \quad in \quad 1L)}$

$Molarity =\frac {0.581}{0.1} =5.81 M$