Question

A 12.34 ml solution with an unknown salt concentration had a mass of 10.25g. when the water was evaporated from the solution 4.78 g of NaCl remained. Calculate the molarity of NaCl in the solution.

Answer 1

Answer : The molarity of NaCl in the solution is, 6.62 M

Solution : Given,

Mass of NaCl = 4.78 g

Molar mass of NaCl = 58.5 g/mole

Volume of solution = 12.34 ml

Molarity : It is defined as the number of moles of solute present in one liter volume of solution.

Formula used :

$Molarity=\frac{\text{Mass of NaCl}\times 1000}{\text{Molar mass of NaCl}\times \text{volume of solution}}$

$Molarity=\frac{4.78g\times 1000}{58.5g/mole\times 12.34ml}=6.62mole/L=6.62M$

Therefore, the molarity of NaCl in the solution is, 6.62 M

Answer 2

Hey there!

Mass of NaCl = 4.78 g

Molar mass of NaCl = 58.44 g/mol

Volume of solution = 12.34 mL

Number of moles:

n = mass of solute / molar mass

n = 4.78 / 58.44

n = 0.08179 moles of NaCl

Volume in liters:

12.34 mL / 1000 => 0.01234 L

Therefore:

Molarity = number of moles / Volume ( L )

Molarity = 0.08179 / 0.01234

Molarity = 6.62 M

Hope that thelps!