Question

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1. If you perform a 1:5 dilution of a 1M solution, how many parts of the 1M solution do you use, and how many parts of the diluent do you use?

2. You have a 5X stock solution. You want to make 100 ml of a 0.5X solution. How would you determine the volume of the 5X solution and the diluent to use?
   1. Show the amount that you calculated of the 5X solution.
3. 2. How much diluent do you add to the solution to generate the 0.5X solution?

3. You want to perform a serial dilution using four consecutive 1:10 dilutions on a solution (Solution A), and end with 200 µl of your final solution:
   1. How would you do this? Explain.
4. 2. What is the concentration of your final solution compared to your initial solution? If you started with a solution that was 1X, what is the final solution in terms of X?

Answer 1

- For 1: 5 dilution of 1M solution:

Take 1 part of 1M solution and 4 parts of diluents

For example, if you are interested to dilute 20ml of 1M solution in 1:5 then you have to take 20ml of 1M solution (1 part) and further add 80 ml diluents (4 parts, 4 x20= 80ml). The final volume is 100ml and the concentration is 1/5^th of 1M solution (0.2M).

- To make 0.5X solution form a stock of 5X:

Use the formula; C1 x V1 = C2 x V2

C1 = Concentration of stock solution (5X)

C2 = Concentration of final solution

V1= volume of stock (5X) required

V2= final volume of diluted solution

As per the statement, the final volume should be 100ml ( V2), stock concentration (C1= 5X), final concentration (C2=0.5). To find out the stock volume required for dilution (V1?)

                        C1 xV1 = C2 x V2

                        5 x V1 = 0.5 x 100

                        V1 = 10ml

So the 10ml of stock (5x) should be added in 90 ml of diluents to form a 0.5x solution of 100 ml

A) 10 ml (5x) stock required

A) 90 ml diluents required

The answer of serial dilution question: explanation see in the figure attached4

- The concentration of final solution id 1/10000 x

See the details in the figure attached