Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Finding the emiprcal formula

  1. Jun 8, 2008 #1
    1. The problem statement, all variables and given/known data

    A metal alloy consists of aluminium and zinc. When a 1.00 g sample of alloy is reacted with excess HCl, 0.0610 g of hydrogen gas forms. Calculate the percent composition of the alloy.

    3. The attempt at a solution

    Set up a balanced equation then calculated the relative moles and grams of the elements and compounds

    AlZn + HCl -> H2 + AlCl + HZn is the product correct?
  2. jcsd
  3. Jun 8, 2008 #2


    User Avatar
    Science Advisor

    If the reaction runs at all, yes, that is the correct product. Whether it will run or not depends on whether AlCl is more "stable" than AlZn. And, of course, you haven't yet balanced the equation.
    Last edited by a moderator: Jun 8, 2008
  4. Jun 8, 2008 #3


    User Avatar
    Staff Emeritus
    Science Advisor
    Homework Helper

    AlZn is the formula for a 50/50 alloy. We do not know that is the case, so this formula has to be written in a more general form.
  5. Jun 8, 2008 #4


    User Avatar
    Science Advisor
    2017 Award

    An alloy is a physical mixture, not a chemical compound. Thus, the two substances in your alloy are Al and Zn, not some chemical compound composed of Al and Zn. Thus, you have to consider two separate reactions, the reaction between Al and HCl and the reaction between Zn and HCl.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook