1. What dilution did I make?!? An introduction to dilutions

2. Dilutions are fractions When we add water to orange juice concentrate to make orange juice for breakfast, we are making a dilution. The dilution that we have made can be determined by the expression: Parts of orange juice concentrate Total parts of prepared orange juice

3. Preparing orange juice If we follow the directions to make orange juice from concentrate, we add 3 cans of water to one can of orange juice concentrate: OJ H2OH2OH2OH2OH2OH2O The final concentration of the orange juice is 1/4 of the original concentration Dilution: 1 can orange juice 4 cans total

4. Preparing orange juice If we like our orange juice less strong, we can add more water: OJ H2OH2O H2OH2OH2OH2O The final concentration of the orange juice is 1/5 of the original concentration Dilution: 1 can orange juice 5 cans total H2OH2O

5. Preparing orange juice If we like our orange juice stronger, we can add less water: OJ H2OH2OH2OH2O The final concentration of the orange juice is 1/3 of the original concentration Dilution: 1 can orange juice 3 cans total

6. 1/3 dilution 1/4 dilution 1/5 dilution Note that, as the fraction representing the dilution gets smaller, the color of the orange juice becomes lighter. This is because you are diluting the orange juice more with additional water.

7. It’s easy to determine the dilution made: The dilution is: parts of solute* total parts of solution** *Solute--the liquid you are diluting **Solution--the combination of solute and water

8. “Parts” can be anything… (as long as they are the same….) A 1/3 dilution could be: 1 can solute 3 cans solution

9. Parts can be anything… (as long as they are the same….) A 1/3 dilution could be: 1 tablespoon 3 tablespoons

10. More commonly… Parts will be some common unit of volume in the lab: 1 mL soluteor1 L solute 3 mL solution3 L solution

11. But…. The “parts” cannot be different: Suppose you added 1 mL of solute to enough water to make 1 L total of solution. What dilution did you make? 1 mL is NOT correctly expressed 1L This dilution would need to be expressed as: 1 mL or 0.001 L 1000 mL 1 L Note that the units do not cancel out! Look! The units cancel! Either expresses a 1/1000 dilution!

12. Just remember…. To find the dilution--just put parts of solute over parts of solution. It doesn’t have to be pretty! Example: If you add 8.3 mL of water to 1.5 mL of solute what dilution have you made? The total volume of solution is 1.5 mL + 8.3 mL = 9.8 mL solution The dilution is: 1.5 mL solute=1.5 9.8 mL solution 9.8 Well… That’s not a pretty dilution, but it was easy to figure out!!!