how to prepare 35ml 70% of ethanol from 250ml 100% of ethanol?

Answer 1

Use the formula:
C1V1=C2V2
Where
C1 is concentration 1
V1 is volume 1
C2 is concentration 2
V2 is volume 2
then
70%x=100%250ml
x=100%250ml/70%
x=100*250ml/70
x=10*250ml/7
x=357,14ml
so you need to add the difference in water (or the solvent you are using), in this case 107,142ml
then you will have 357,14ml 70% ethanol solution. Just take the 35ml you need.

Answer 2

Take 24.5 ml of 100% ethanol and dilute it to 35ml (with H2O).

Answer 3

7/10 of your final solution needs to be ethanol. 70% of 35 ml is 24.5 ml, so measure out that much ethanol, and add 10.5 ml of the necessary dilutant, whatever that is.

Answer 4

That's easy, get 24.5 ml pure ethanol and dilute to until you have 35 ml

Answer 5

Pay attention to the significant number!
It's a dilution question:
Use M1V1=M2V2
M1=100
V1=?
M2=70
V2=35

Therefore V1=24.5mL and you should round it to 24mL (sig. fig. and round to nearest even number; notice that 24.5mL is wrong becuase your answer should have only 2 sig. fig. not 3)

Add 24mL of 100%ethanol and dilute it to 35mL.

Answer 6

take 24.5 ml of the pure ethanol, and add 10.5 ml of H2O