Question

equal amounts of solutions of NaOH having concentration 10%(wt/wt) and 20%(wt/wt) are mixed. What will be molality of the NaOH in the resulting solution?​

Answer 1

equal amounts of solutions of NaOH having concentration 10%(wt/wt) and 20%(wt/wt) are mixed.

in 10%(W/W) NaOH solution, 10g of NaOH presents in 100g of solution.

and in 20% (W/W) NaOH solution, 20g of NaOH presents in 100g of solution.

let's take 100g of each of solutions.

so, total mass of solute = 10g + 20g

= 30g

and total mass of solvent = (100 - 10)g + (100 - 20)g

[as we know, mass of solution = mass of solute + mass of solvent ]

= 90g + 80g = 170g

now, no of moles of solute = mass of solute/molar mass of solute

= 30g/40g/mol [ molar mass of NaOH = 40g/mol ]

= 0.75 mol

now, molality = no of moles of solute/mass of solvent in Kg

= 0.75/(170/1000)

= 750/170

≈ 4.41m

Answer 2

Explanation:

refer above attachment .