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

Rate of reaction of Mg and HCl

  1. Feb 22, 2010 #1
    I have to do a lab investigating factors that affect the rate of reaction between Mg(s) and HCl(aq). I decided to change the concentration of HCl. I timed how long it took for the Mg to completely disappear when the HCl was in excess and the amount of Mg used is constant. Obviously the higher the concentration, the lower the time, the faster the rate of reaction. My question is that since I'm using solid Mg, I can't really talk about the concentration of that... so is it simply enough to say that the lower times means that the rate is faster? I can't say rate=Delta[Mg]/Delta(t) if there's no concentration of Mg. I'm just confused on how to correctly explain this without a concentration, what do I do?
  2. jcsd
  3. Feb 23, 2010 #2
    Nevermind, I figured out the moles of a product using stoich. and then I could find the molarity of that :)
  4. Feb 23, 2010 #3


    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    Nevertheless, things do get tricky when it comes to defining concentrations (or activities) of solids. For the scope of this lab, I think you would be well-advised to be consistent with your use of Mg ribbons between different runs - make sure they have the same mass and roughly the same surface area.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook