1. Anthony Gates DCSD: Dubuque Senior High School
Molarity/Solutions
Anthony Gates
DCSD: Dubuque Senior High School

2. Vocab: Be a part of the solution!
Solute: The particles that become dissolved.
Solvent: the dissolving medium (what the solute dissolves in).
Aqueous Solution: solution where the solvent is water.
Concentration: a measure of the amount of solute that is dissolved in a given quantity of solvent.

3. Big Idea
Molarity (M): concentration of a solution described as the number of moles of solute per liter of solution.
1M = 1mol/L

4. Kool-aid HOW DO PEOPLE MAKE KOOL-AID?
Dissolve a precise amount of solid into water.
How does one know how much kool-aid powder to add to the water? … people add it all… well how do they know how much to put in the pouch? … By mass

5. Fun Times…

6. Solution making 101
To reach a specific concentration of solution, we must carefully calculate and measure out both the solute and the solvent.
𝑚𝑎𝑠𝑠 𝑜𝑓 𝑡ℎ𝑒 𝑠𝑜𝑙𝑢𝑡𝑒= 𝑑𝑒𝑠𝑖𝑟𝑒𝑑 𝑚𝑜𝑙𝑎𝑟𝑖𝑡𝑦 𝑚𝑜𝑙𝑎𝑟 𝑚𝑎𝑠𝑠 𝑑𝑒𝑠𝑖𝑟𝑒𝑑 𝑣𝑜𝑙𝑢𝑚𝑒
Volume must be in Liters!

7. Let’s Practice (Facciamo un pò di pratica)
What is the mass of Ba(NO3)2 needed to make 250ml of a 1.0M solution?
X = (1.0M)(261.32𝑔/𝑚𝑜𝑙)(.250L) = 65.33g Ba(NO3)2

8. Practice makes Perfect (La pratique rend parfait)
What is the concentration that will be made if g of ZnO is dissolved in enough water to form 500ml of solution?
20.35g = (X)(81.39𝑔/𝑚𝑜𝑙)(0.500L)
X = 0.5M

9. Dilutions
Diluting a solution reduces the number of moles of solute per unit volume, but the total number of moles of solutes in solution does not change.

10. Calculations with Dilutions
M1V1 = M2V2
(Molarity)(Volume) = (Molarity)(Volume)

11. Dilution Practice
Mr. Gates wants to make 250ml of 6M HCl. How much concentrated acid (12M) is needed to make this?
(250ml)(6M) = (12M)(V2)
V2 = 125ml concentrated acid is needed.

12. How much 1.6M NaCl can be made from 500ml of 3M NaCl?
Extra Practice
How much 1.6M NaCl can be made from 500ml of 3M NaCl?
937.5ml

13. práctica adicional
Austin and Mackenzie dilute 50ml of an unknown concentration of KOH until it new volume is 325ml. After performing a chemical reaction they come to the conclusion that the new concentration is 0.98M. What was the original concentration?
6.37M

14. zusätzliche Übung (Additional Exercise)
Tyler and Kendra were diluting 25ml of a solution originally at 18M by adding 775ml of water to it. What is the new concentration?
0.56M