Complete the following questions and problems relating to molality.
1. Write the equation for molality:
2. Write the equation for molarity:
3. Explain in words how molality and molarity differ.
4. What is the molality of a solution in which 0.32 moles aluminum chloride has been
dissolved in 2,200 g water?
5. What mass of water is needed to prepare a 1.20 molal solution using 0.60 mol
propyleneglycol?
6. What is the molality of a solution in which 0.145 mol carbon dioxide is dissolved in 591
mL water?
7. What is the molality of a solution in which 13.7 g sodium chloride has been dissolved in
500.0 g water?
8. How many grams of ethanol, C2H6O, are need to prepare a 0.10 m solution using 1.000
kg water?
9. What is the molality of the solution is which 3.0 moles of sodium chloride is dissolved
into 1.5 kg of water?
10. What is the molality of a solution in which 25.0 grams of sodium chloride is dissolved in
2000 mL of water?
11. What is the molality of a solution that contains 63.0 g HNO3 in 0.500 kg H2O?
12. What is the molality of a solution that contains .500 mol HC2H3O2 in 0.125 kg H2O?
13. What mass of water is required to dissolve 100 g NaCl to prepare a 1.50 m solution?
14. What mass of water must be used to dissolve 0.500 kg C2H5OH to prepare a 3.00 m solution?
15. What mass of H2SO4 must be dissolved to 2.40 kg H2O to produce a 1.20 m solution?
16. What is the number of molecules of C2H5OH in a 3 m solution that contains 4.00 kg H2O?
17. What is the molality of a solution that contains 80.0 g Al2(SO4)3 in 625 g H2O?
18. What mass of water is required to dissolve 175 g KNO3 to produce a 2.25 m solution?
19. What mass of HC2H3O2 must be dissolved in 800 g H2O to produce a 6.25 m solution?
20. How many moles of NH4+ ions are dissolved in 0.750 kg of H2O when the concentration of (NH4)3PO4
is 0.400 m?
21. What is the molality of a saturated solution of NaNO3 at 20oC (Use the solubility graph for this
question)?
22. What is the molality of a saturated solution of NH4Cl at 70oC (Use the solubility graph for this
question)?
23. What is the molality of a solution made from 2.4 moles of NaCl and 0.80 kg of water?
24. What is the molality of a solution made from 63 g of HNO3 in 0.50 kg of water?
25. 25 g of NaOH is dissolved in 120 g of water. What is the molality?
26. How much water is needed to make a 1.40 m solution from 0.400 moles of H2SO4?
27. How much water is needed to make a 0.50 m solution from 3.2 g of NaCl?
28. What mass of CH3OH is needed to add to 1.20 kg of water to make a 3.00 m solution?
29. In order to make a 0.60 m solution, what mass of K3PO4 is needed to add to 400 mL of water?
30. 4.5 g of NH4Cl is added to 225 mL of water. What is the molality?
31. A solution of MgBr2 is 1.40 m. What is the molality of bromide ions in solution?
32. What is the molality of ions in solution if 2.0 moles of Al(NO3)3 is added to 2.5 kg of water?
33. How many moles of ions are dissolved in 0.75 kg of water when the concentration of (NH4)3PO4 is
0.40 m?
34. A solution of Ca(NO3)2 must be 2.00 m in ions. What mass of Ca(NO3)2 must be added to 125 g of
water to make this solution?