Unit 2 Test Review Flashcards
What is the equation for molarity?
M= moles of solute/liters of solution
A solution is prepared by dissolving 24.9 g of CaCl2 in 210 mL of solution. What is the molarity?
1.1 M
A solution contains 12.9 g of Na2SO4 in 325 mL of solution. What is the molarity?
0.28 M
Consider 670 mL of a 4.1 M solution of Mg(NO3)2 setting in a beaker. If you evaporate all 670 mL of the solution, how many grams of solute would be left in the beaker?
400 g
What is the equation for molality?
m= moles solute/kg solvent
1 kg of water = ?
I L
1 g of water = ?
1 mL
What is the molality of a solution that is made by dissolving 32.6 g of Na2SO4 in 475 g of water?
0.48 m
What is the equation for mole fraction?
Xsolute= mol solute/(mol solute + mole solvent)!
What is the mole fraction of nacl when 14.25 g of nacl is dissolved in 85.0 g of H2O.
0.1
Calculate the mass percent of Na3PO4 if 12.5 g of it are dissolved in 250 mL of water.
4.76%
In colder climates during the winter, people put salt on the roads and walkways to melt ice. Why do people do this? Why does salt melt ice?
Because salt lowers the freezing point so that water will not freeze until much lower temps
A solution is prepared by dissolving 45.7 g of Na2CO3 in 200 g of water.
a) what is the molality?
b) what is the total molality of all the particles in the solution?
2.15 m; 6.48 m
Change in boiling point equation?
🔼T= (mT)(Kbp)
What is the boiling point elevation constant?
0.515
What is the freezing point depression constant?
1.853
What is the freezing point of a 2.5 m solution of salt water?
-9.3
Do you subtract from 0 or add to 100 with freezing point?
Subtract from 0
Do you subtract from 0 or add to 100 with boiling point?
Add to 100
Dilution causes the concentration of an unsaturated solution to
Decrease
Evaporation causes the concentration of an unsaturated solution to
Increase
What is the concentration?
Amount of solute per solvent
