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: Stoichiometry - transferable mole values?

  1. Sep 17, 2008 #1
    1. The problem statement, all variables and given/known data

    I have to find the mass of HCl (in grams) that is produced given the below reaction yields 18.7g of H3PO4.

    2. Relevant equations

    PCl5 + 4H20 -> H3PO4 + 5HCl

    3. The attempt at a solution

    I calculated the # of mols for H3PO4.

    I want to confirm if this mol value (0.190815119mol) is also the # of mol of H and # of mol of Cl, with regrards to HCl.. or is the number of mols of each of H and Cl fives times that of 0.190815119mol because of the coefficient "5"HCl ?

  2. jcsd
  3. Sep 17, 2008 #2


    User Avatar
    Homework Helper
    Education Advisor
    Gold Member

    Calculate formula weight of phosphoric acid; use this to find moles of phosphoric acid.
    Use stoichiometric mole ratio found in the reaction statement to calculate moles of resulting HCl.
    Calculate formula weight of HCl and use this to calculate the mass of HCl.
  4. Sep 17, 2008 #3


    User Avatar
    Science Advisor
    2017 Award

    The chemical equation says that for each mole of PCl5 consumed you get 5 moles of HCl, so you would need to multiply 0.191 mol by 5 to get the number of moles of HCl.
  5. Sep 18, 2008 #4
    Alrighty, thanks for the clarification!
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook