Question

Problem 1: If seawater contains 40g of sodium chloride per 500ml, then

what is the molarity of a solution?

Answer 1

Explanation: Molarity= Number of moles of solute

Volume of solution in liters

given,

mass of solute, NaCl= 40g

volume of solution = 500ml = 0.5L

number of moles of solute = mass in grams

molecular mass

Molecular mass of NaCl = 23*1 + 35.5*1

= 23 + 35.5

= 58.5g

no. of moles = 40/58.5

= 0.68 mol

molarity = 0.68/0.5

=
`(68*10^(-2))/(5*10^(-1))`

=
`13.6* 10^(-1)`

= 1.36 M