Dilutions Preparing Dilutions Concentrated solutions that are diluted
- Slides: 10
Dilutions
Preparing Dilutions �Concentrated solutions that are diluted before use to a specified concentration and volume are frequently used in the laboratory. �However this can create a problem. How much of the stock do you remove and how much diluent do you add to it to produce a solution of a certain concentration and volume?
Dilution Factors �Suppose that 10 m. L of a stock solution is removed and is diluted with 40 m. L of buffer. �This is a 10 m. L/50 m. L dilution, which equals a 1/5 dilution (the units cancel). �The dilution factor is “ 1/5”.
Dilutions & Proportional Relationships �The concepts of dilution and proportion are related. For example: 0. 1 m. L of food coloring mixed with 9. 9 m. L of water is equivalent to 1 m. L of food coloring mixed with 99 m. L of water.
Preparing Dilutions �Suppose you have a liter of 4 M stock solution of GPS buffer and you want to dilute some of it so that you have 200 m. L of 500 m. M GPS. �There are various ways to do this, however, a helpful formula to use is: C 1 V 1 = C 2 V 2 Concentration 1 * Volume 1 = Concentration 2* Volume 2
Applying C 1 V 1 = C 2 V 2 �Consider first, is this a situation where a less concentrated solution is being made from a more concentrated solution? �Yes. Therefore, it is appropriate to apply the M 1 V 1= M 2 V 2 equation (*Note: ‘M’ is used for dilution problems involving molarity, ‘C’ is used for problems involving ratio and percent concentrations).
Applying C 1 V 1 = C 2 V 2 1. ) Concentrated solution = 2 M = M 1 2. ) The volume of concentrated stock necessary is ? (what you want to calculate, how much stock to take out to make the desired dilution) = V 1 3. ) The concentration you want to prepare is 500 millimolar = M 2 4. ) The volume you want to prepare is 200 m. L = V 2 (in a real laboratory situation, you will decide what the volume will be)
Applying C 1 V 1 = C 2 V 2
Applying C 1 V 1 = C 2 V 2 �C 1 V 1 = C 2 V 2 can also be used when preparing solutions with more than one stock involved. �Simply determine V 1 for each component of the desired solution while using the desired final concentration and volume for C 2 V 2
Dilution Labs All these calculations and procedures will be much clearer after you do the Dilutions Lab!