January 11, 2025, 11:17:34 PM
Forum Rules: Read This Before Posting


Topic: Checking if a test question is right  (Read 2733 times)

0 Members and 4 Guests are viewing this topic.

Offline todd710

  • Very New Member
  • *
  • Posts: 2
  • Mole Snacks: +0/-0
Checking if a test question is right
« on: November 09, 2010, 01:29:17 PM »
Consider the reaction 2Al(s) + Fe2O3(s) --> 2Fe(l) + Al2O3(s). If 2 moles of Al(s) and 3 moles of Fe2O3(s) are available at the start of the reaction.

Question: Which substance will be the limiting reactant?

The answer key has the answer "Al(s)" but my son has the answer "Al" and insists it is right.  I know the answer is Al(s) but cannot adequately explain why?.  Could some expound?

TIA

Todd

Offline crosemeyer

  • Regular Member
  • ***
  • Posts: 27
  • Mole Snacks: +3/-0
Re: Checking if a test question is right
« Reply #1 on: November 09, 2010, 01:36:20 PM »
I think the (s) and (l) simply denote solid and liquid.

Offline todd710

  • Very New Member
  • *
  • Posts: 2
  • Mole Snacks: +0/-0
Re: Checking if a test question is right
« Reply #2 on: November 09, 2010, 02:20:27 PM »
I think the (s) and (l) simply denote solid and liquid.

I agree.  If I were to state the answer as "Al(g)" would that be correct?  If I put down "Al" it the "(s)" assumed?

Offline Borek

  • Mr. pH
  • Administrator
  • Deity Member
  • *
  • Posts: 27895
  • Mole Snacks: +1816/-412
  • Gender: Male
  • I am known to be occasionally wrong.
    • Chembuddy
Re: Checking if a test question is right
« Reply #3 on: November 09, 2010, 02:37:54 PM »
Al(g) would not make much sense, as you need quite high temperature to boil Al.

Al(s) vs Al - a lot depends on the teacher. I would accept (in this case) both answers, but some are nitpicky and they may want Al(s).
ChemBuddy chemical calculators - stoichiometry, pH, concentration, buffer preparation, titrations.info

Sponsored Links