You are given 1.0 mL of the enzyme amylase and need to add cold 95% ethanol to reach a final concentration of 40% ethanol in the sample. What volume of the 95% ethanol did you need to add to the enzyme solution to obtain this concentration? (note: this one is a litle tricky-you will need to account for the starting volume of the enzyme solution.)

0,727 mL

Explanation:

We add x mL of the 95% ethanol solution to 1 mL: C1=0,95 and V1=x mL

As we already had 1 ml of solution, now we'll have (1 + x) mL of the 40% ethanol solution: C2=0,4 and V2=1+X mL

Now, using the C1V1=C2V2 equation:

(0,95) x=0,4 (x+1)

0,95x=0,4x + 0,4

0,95x-0,4x=0,4

0,55x=0,4

x=0,4/0,55=0,727 mL

Therefore, we need to add 0,727 mL of a 95% ethanol solution to the enzyme solution to obtain a final concentration of 40% ethanol.