1. Warm-up #17
If the solubility of dinitrogen oxide gas is g/100g water at 20°C and 2.0 atm of pressure. What would the solubility be at standard atmospheric pressure?
How many grams of NaCl can dissolve in 2.0 L of water at 20°C to make a saturated solution? The solubility of sodium chloride at this temperature is 36g/100g water.

2. Dilutions and Solubility Guidelines
Molarity and Molality
Dilutions and Solubility Guidelines

3. Concentration of Solutions
Concentration—measurement of how much solute is in a given amount of solvent.
Diluted solution—a relatively small amount of solute.
Concentrated solution—a relatively large amount of solute.
These are not very definite terms.

4. Molarity
Molarity is the number of moles of solute in one liter of solution.
This is a quantitative description. Symbol is M
Be careful: This is different from the number of liters of solvent.
Formula: 1M= 1 molar solution=1mole solute
1 liter of solution

5. Practice Problem 1
What is the molarity of a salt solution made by dissolving mg of NaCl in 2.00 mL of water? Assume the final volume of the solution is the same as the volume of the water.
2.40 M

6. Practice Problem #2
What is the molarity of a solution that contains g of acetic acid, CH3COOH, dissolved in enough acetone to make mL of solution?
6.494 M

7. Practice Problem #3
What mass of magnesium bromide would be required to prepare 720 mL of a M aqueous solution?
12.4 g

8. Molality
Molality—a way to express the solute to solvent ratio, molal concentration.
Symbol=μ or cursive lower case m
Number of moles of solute dissolved in 1 kg of solvent. 1 molal solution=1 mole solute kg solvent

9. Formula
molality=mole solute kg solvent Conversions: 1 kg=1000g 1 g H2O=1 ml H2O

10. Practice Problem #1
Determine the molality of a solution of 560 g of acetone, CH3COCH3, in 620 g of water.
16 μ

11. Practice Problem #2
How many moles of 2-butanol, CH3CHOHCH2CH3, must be dissolved in 125 g of ethanol in order to produce a 12.0 μ 2- butanol solution? What mass of 2-butanol is this?
1.50 mol 2-butanol
111 g 2-butanol

12. Practice Problem #3
What is the molality of a solution of 12.9 g of fructose, C6H12O6, in 31.0 g of water?
2.31 μ

13. Making Dilutions M1V1= M2V2 M=Molarity & V=Volume
Dilute 1.0L of 5.0 M SrS to 2.0M. What is the final volume?
(5.0 M SrS)(1.0L) = (2.0M SrS)(V2)
V2 = 2.5 L
How much water would you need to add?
If the total volume = 2.5L & original volume is 1.0L
Need to add 1.5L of water to make the dilution

14. Let’s Practice
How would you prepare 100. mL of a M HNO3 solution if you have a 12.0 M stock solution of HNO3?
M1V1=M2V2
M1=12.0 M
V1=?
M2=0.500 M
V2=100.mL
V1=4.17 mL
Amount of water added to V1=95.83 mL

15. Solubility Guidelines
Table 1 page 437

16. Molarity Worksheet

17. Homework—Due Tuesday 3/30
Molarity Worksheet