Question

Help with Molarity? What mass of water must be used to dissolve 500g C2H5OH to prepare a 3.00 m solution?

2.6 kg


1.65 kg


5.2 kg


3.87 kg
What is the molality of a solution that contains 80.0 g Al2(SO4)3 in 625 g H2O?
0.578 m


0.476 m


0.374 m


0.213
25 g of NaOH is dissolved in 120 g of water. What is the molality?
5.21 m


4.16 m


3.74 m


7.32 m

Answer 1

What mass of water must be used to dissolve 500g C2H5OH to prepare a 3.00 m solution?

500g C2H5OH ( 1 mol / 46.07 g ) / 3 mol/kg water = 3.62 kg water needed


What is the molality of a solution that contains 80.0 g Al2(SO4)3 in 625 g H2O?

Molality = 80.0 g Al2(SO4)3 (1 mol / 342.15 g) / .625 kg H2O = 0.374 m


25 g of NaOH is dissolved in 120 g of water. What is the molality?

Molality = 25 g NaOH ( 1 mol / 40 g ) / .120 kg = 5.21 m