Answer:
0.074
Explanation:
15% means that in 100 g of solution 15 g sodium hydroxide is present.
Mass of water = 100 - 15 = 85 g
Number of moles of sodium hydroxide:
Number of moles = 15 g/40 g/mol
Number of moles = 0.375 mol
Number of moles of water:
Number of moles = 85 g/18 g/mol
Number of moles = 4.7 mol
Moles fraction of NaOH:
moles of NaOH/ moles of solvent + moles of solute
0.375 mol/ 0.375 mol+4.7mol
0.375 mol / 5.075 mol
0.074
