Chemistry

You have 100.0 mL of 0.2500 M solution of NaCl sitting in a beaker. After several days you test the solution and find out that it is now 0.3721M. How much water must have evaporated??

I got 67.2 mL but its the wrong answer.. PLS HELP!

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  1. use mmoles as mmoles at end mus be same as at start.

    100.0 ml x 0.2500 M = (final vol) x 0.3721 M

    so final volume =
    100.0 ml x 0.2500 M/0.3721 M

    I got 53.75 ml as the final volume.

    hence you can calculate how much water has evaporated.

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  2. Thank you for your help :) but the correct answer according to my prof was 32.8mL i am not even sure if C is the correct answer or a typo.

    I was give 5 options to choose from:
    a) concentration can not change because of evaporation
    b) 100.0 mL
    c) 32.8 mL
    d) 67.2 mL
    e) 12.2 mL

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  3. oops
    Sorry a typed 100.0 ml x 0.2500 M/0.3721 M but put 0.2000 into my calculator!!

    I got 67.186 ml as the final volume.

    Yes, so C

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  4. what is 4.00g KCI in 40.0mL of solution. give answer to two significant forms

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  5. EX予約

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