Question

what volume of 20% sucrose would you use to make 2ml of 5% sucrose solution?

Answer 1

20% means 20 g per 100 mL.

2 mL of 5% = 2 mL * 5 g / 100 mL = 0.1 g.

( 0.1 / 20) * 100 mL = 0.5 mL

Answer 2

Answer: 0.5 ml

Explanation: As the number of moles remain same, we can write:

$C_1V_1=C_2V_2$

where $C_1$ = concentration of first solution

$V_1$ =volume of first solution

$C_1$ = concentration of second solution

$V_2$ =volume of second solution

$20\%\times V_1=5\%\times 2ml$

$V_1=0.5ml$

The volume of 20% solution used is 0.5 ml.