You need a 30% alcohol solution. On hand, you have a 90 mL of a 45% alcohol mixture. How much pure water will you need to add to obtain the

Question

You need a 30% alcohol solution. On hand, you have a 90 mL of a 45% alcohol mixture. How much pure water will you need to add to obtain the desired solution?

You will need
_____ mL of pure water
to obtain
______ mL of the desired 30% solution.

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Raelynn 16 mins 2021-09-15T03:17:15+00:00 1 Answer 0

Answers ( )

    0
    2021-09-15T03:18:48+00:00

    Answer:

    45ml of pure water to obtain 135ml of the desired 30% solution

    Step-by-step explanation:

    45% of 90 = 40.5

    So, 40.5ml of alcohol in 90ml

    We want 30% and therefore need a ratio of 3:7

    40.5รท3=13.5

    so one part of our ratio is 13.5

    we then times this by 7

    13.5 x 7 = 94.5

    so, 94.5ml of water

    to work out how much we already have, we should do 90ml- 40.5ml = 49.5ml

    and then 94.5- 49.5 = 45ml

    We need 45ml of water and the total mo of the desired solution will be 90+45=135ml

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