Question

Starting with a 7. 0 x 10-5 M. Allura Red stock solution you will need to calculate the volumes required to prepare 10.00 mL solutions of 3.5 x 10-5 M, 2.8 x 10-5 M, 2.1 x 10-5 M, 1.4 x 10-5 M, and 3.5 x 10-6 M before coming to lab. What volume of the stock solution will be required to prepare 10.00 mL of a 2.1 x 10-5 M solution of Allura Red?

Answer 1

1) 5.0 mL, 4.0 mL, 3.0 mL and 2.0 mL respectively.

2) 3.0 mL

Step-by-step explanation:

Hello there!

1) In this case, by considering that the equation we use for dilutions contain the initial and final concentrations and volumes:

`C_1V_1=C_2V_2`

For the first four solutions, we compute the volume of the stock one (V1) as shown below:

`V_1=(C_2V_2)/(C_1)`

Thus, we obtain:

`V_1^1=(3.5x10^(-5)M*10.00mL)/(7.0x10^(-5)M) =5.0mL\\\\V_1^2=(2.8x10^(-5)M*10.00mL)/(7.0x10^(-5)M) =4.0mL\\\\V_1^3=(2.1x10^(-5)M*10.00mL)/(7.0x10^(-5)M) =3.0mL\\\\V_1^4=(1.4x10^(-5)M*10.00mL)/(7.0x10^(-5)M) =2.0mL`

2) In this case, for a final concentration of 2.1x10-5 M and a volume of 10.00 mL, the volume of the stock solution would be:

`V_1=(2.1x10^(-5)M*10.00mL)/(7.0x10^(-5)M) =3.0mL`

Best regards!