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Homework Help: Beginner chemistry

  1. Oct 15, 2006 #1
    Hi, i'm pretty new to chem, I have a few questions:

    Metals react with dilute sulfuric acid to give hydrogen according to:
    M +H2SO4------>MSO4 + H2

    when 5.00g of a mixture of Mg and Zn were dissolved in sulfuric acid 0.284g of H was collected. What was the composition of the mixture of Mg and Zn expressed as a percent mass?

    im confused, what do I do when im given that there is 5.00g of mixture?what do I do about molar mass etc...

    Last edited: Oct 15, 2006
  2. jcsd
  3. Oct 15, 2006 #2
    I also dont know what to do because no formula is given for the Zinc Magnesium mixture?
  4. Oct 16, 2006 #3


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    Homework Helper
    Gold Member

    The question asks you to find how much of the 5.00g was Mg, and how much was Zinc. Since that's what you want to find, let's call the amount of Mg which was present initially as x gms.

    The reaction given to you is

    M +H2SO4------>MSO4 + H2

    where, M can be Mg or Zn (ie, both Mg & Zn react the same way).

    Now, find out how many grams of hydrogen was produced if x gms of Mg completely reacted to form H2. (convert x gms of Mg to gm-moles of Mg first. 1 mol of M reacts to form ___ mol of H2)
    Similarly, find out how many gms of hydrogen was produced if 5-x gms of Zn completely reacted to form H2. Since the total mass of H2 formed is given, you can solve for x.

    Can you take it from here?
    Last edited: Oct 16, 2006
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