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Homework Help: What is the right amount of citric acid and sodiumhypophosphite?

  1. Feb 6, 2016 #1
    1. The problem statement, all variables and given/known data

    In the materrials and methods of one article is mentioned that: A specific amount of citric acid and the catalyst sodium hypophosphite (50 % w/w, on weight of citric acid used) was dissolved in the starch solution.

    My question is how much citric acid and sodium hypophosphite I need to weigh on the balance?

    p.s: In one part of article is written: Films were cast from 3 % starch and cross-linked using 5 % (w/w) citric acid.
    2. Relevant equations

    3. The attempt at a solution

    50 % w/w so we need to weigh 50 g or mg of citric acid + 50 g or mg of sodium hypophosphite.

    But why in another part of article mentioned 5 % of citric acid was used? I am confused!
    Last edited: Feb 6, 2016
  2. jcsd
  3. Feb 7, 2016 #2
    I calculated like this. I want to make 3 % of starch so I weigh 3 gram of starch. Then 5 % of citric acid which is 1.28 gram then catalyst 50 % which becomes 0.64 gram. Then I will add 96.23 gram of water. Am I right?
  4. Feb 7, 2016 #3
    Any feedback?
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