A solution is prepared by dissolving 4g of NaOH in 100 g H2O. The volume of the resulting solution is 102mL.?

Question

a. What si the mole fraction of NaOH

b. molarity of solution

c. molality of solution

d. mass percent of NaOH

e. density of solution

PLEASE HELP T_T

Answer 1

Work out how many moles of NaOH you have first.

moles of NaOH = mass / molecular weight

molecular weigth NaOH = 22.99 + 16.00 + 1.008 = 39.998 g/mol

moles NaOH = 4 g / 39.998 g/mol

= 0.100 moles

moles of water = mass / molecular weight

molecular weight H2O = 1.008 x 2 + 16.00 = 18.016 g/mol

moles = 100 g / 18.016 g/mol

= 5.55 moles H2O

a) mole fraction = moles of solute / total moles of solution

= moles NaOH / (moles H2O + moles NaOH)

= 0.1 / (5.55 + 0.1)

= 0.0177

b) Molarity = moles of solute / litres of SOLUTION

M = 0.100 / 0.102 L

= 0.98 M

c) molality = moles of solute / kg of SOLVENT

m = 0.100 / 0.100 kg

= 1 molal

d) mass percent weight / volume

= 4 / 102 X 100/1

= 3.92 % w/v

e) density = g / ml

=4 g / 102 ml

= 0.0392 g/ml