Question

If you were preparing a series of two 10% dilutions of pretend 1M HCl. You would have 3 test tubes labeled, 1, 2 and 3. Test tube 1 would be filled with 10 mL of the 1 M HCL. Always Add Acid to Water. This rule must be followed in order to prevent splattering of the acid.

Use the formula to determine how much water should be added to test tube #2 to prepare a 10% dilution. The final desired volume for this dilution is 10 mL. Remember water must be added first!

Vi X Ci = Vf X    Cf

n X 1M HCl = 10 mL X 0.1M HCl    n = 10 mL X 0.1 M

                                                                                    1M

n = volume of 1M HCl used to make the new solution

           

n = 1 mL of 1M HCl

     10 mL (final volume)

   – 1 mL   (volume of the 1M HCl)

       9 mL (volume of water used for the dilution)

1. How much water needs to be added to test tube 2?
2. How much HCL from test tube 1 needs to be added to test tube 2?
3. How would you complete a second 10% dilution in test tube 3 using the contents for test tube 2?
4. Your biology class needs 200 mL of a 0.25M HCl solution. There is a stock bottle containing 500 mL of a 1M HCl solution available for you to use when preparing this solution. Describe how you will prepare the solution. Show your work.

Answer 1

Answer 1. 9 ml of water is needed to add in the test tube 2

Answer 2. 1 ml of 1M HCl is needed to add in test tube no 2

Answer 3. Again 1ml of stock has been talken from test tube no.2 to test tube no 3 already having 9 ml of water.

Answer 4. 50 ml of 1M HCl stock should be added in 150 ml of water to make 200 ml 0f 0.25M HCl.