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Molarity_and_Molality__2

# Molarity_and_Molality__2 - Calculate the molality of...

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Worksheet #2 (Concentration Units: Molarity and Molality) 1. What is the difference between molarity and molality? Write the equations for each of them. 2. What is the molality of a solution containing 7.78g of urea [(NH 2 ) 2 CO] in 203 g of H 2 0? 3. Calculate the molality of a 5.86M ethanol (C 2 H 5 OH) solution whose density is 0.927g/ mL? 4. Calculate the molality of a 44.6% (by mass) aqueous solution of NaCl. 5. The dehydrated form of Epsom salt is magnesium sulfate. What is the percent MgSO 4 by mass in a solution made from 16.0g MgSO 4 and 100mL of H 2 O at 25 o C? The density of water at 25 o C is 0.997 g/mL. 6. Calculate the molarity of a 2.44m NaCl solution given that its density is 1.089g/mL. 7. Concentrated hydrochloric acid is 36.5% HCl by mass. Its density is 1.18g/mL.

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Unformatted text preview: Calculate the molality of concentrated HCl. 8. Calculate the vapor pressure of an aqueous solution of 30 C made from 1.00x10 2 g of sucrose (C 12 O 22 H 11 ) and 1.00x10 2 g of water. The vapor pressure of pure water at 30 C is 31.8mmHg. Answers: 1. Molarity: Easy to measure volume of solution, but volume changes with temperature. This means that molarity can also change. M= mols solute/ L of Solution Molality: Easy to measure stable concentrations of mass because it will not change, but more difficult to with solvents and solutions. m= mols solute/ mass of solvent (kg) 2. 0.638m 3. 8.92M 4. 13.88m 5. 13.8% 6. 2.33M 7. 15.7m 8. 30.2 mmHg...
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