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Chemical arithmetics: Answers not matching

  1. Aug 4, 2014 #1
    Question: 2.0 g of a mixture of Na2CO3 and NaHCO3 was heated when its weight reduced to 1.876 g. Determine the percentage composition of the mixture.

    Attempt: Here is my attempt:


    Problem: My answers do not match those of the text. More critically, the procedure I've adopted is itself inconsistent with that outlined in the text: the "its" in the first line of the problem statement is interpreted in the text as the mass of Na2O alone, whereas I am considering it to be the combined mass of the products (see first 2 lines - chemical reactions - of my attempt above).

    Whose interpretation is correct?

    Would appreciate some thoughts.

    Best regards,
    Last edited: Aug 5, 2014
  2. jcsd
  3. Aug 5, 2014 #2
    For those discouraged to answer, I've removed links to images in my original post and inserted the appropriate image instead.

    Last edited: Aug 5, 2014
  4. Aug 5, 2014 #3


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    Staff: Mentor

    I don't get the light blue comment nor the equation after it.

    Think again: what are the reactions taking place and what are the final products?
    Last edited: Aug 5, 2014
  5. Aug 5, 2014 #4


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    Homework Helper
    Gold Member

    Not gone through. Unfortunate fact: someone else's arithmetic is as attracting as someone else's unmade bed. Despite your colouring etc. is thoughtful and helpful and as good as it gets! :approve:

    However I noticed that in your first equation Na2CO3 went to Na2O. In the second you show Na2CO3 as a product that just stays there. Why wouldn't that also go to Na2O ?
    Last edited: Aug 5, 2014
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