September 15, 2019, 02:17:08 AM
Forum Rules: Read This Before Posting


Topic: percent compositions  (Read 8998 times)

0 Members and 1 Guest are viewing this topic.

momo

  • Guest
percent compositions
« on: May 25, 2004, 09:44:55 PM »
Please help me understanding formulate percentage compositions.

9.03 gMG COMBINED COMPLETELY WITH 3.48 G N TO FORM A COMPOUND.  WHAT IS THE PERCENT CONPOSITION OF THIS COMPOUND?  

Offline Donaldson Tan

  • Editor, New Asia Republic
  • Retired Staff
  • Sr. Member
  • *
  • Posts: 3178
  • Mole Snacks: +261/-12
  • Gender: Male
    • New Asia Republic
Re:percent compositions
« Reply #1 on: May 25, 2004, 11:41:37 PM »
I think u meant "9.03g of Magnesium combined completely with 3.48g of Nitrogen to form a compound. what is the percentage composition of this compond?"

We work by percentage composition by mass.

Using Law of Mass Combination, and that we know
9.03g of Mg reacts completely with 3.48g N2,
the mass of the substance formed = 9.03 + 3.48 = 12.51g

percentage composition of Mg would be
= 9.03g / 12.51g X 100%
= 72.2%

U can obtain the percentage composition of mass for nitrogen using the same method. The idea behind is that u need to know: 100g of the substance formed would contain how many grams of each elemental constituent.
« Last Edit: May 25, 2004, 11:44:18 PM by geodome »
"Say you're in a [chemical] plant and there's a snake on the floor. What are you going to do? Call a consultant? Get a meeting together to talk about which color is the snake? Employees should do one thing: walk over there and you step on the friggin� snake." - Jean-Pierre Garnier, CEO of Glaxosmithkline, June 2006

Offline jdurg

  • Banninator
  • Retired Staff
  • Sr. Member
  • *
  • Posts: 1366
  • Mole Snacks: +106/-23
  • Gender: Male
  • I am NOT a freak.
Re:percent compositions
« Reply #2 on: May 26, 2004, 09:01:57 AM »
Actually Geo, you can't assume that all the ingredients were in a proper molar proportion.  I can almost guarantee that one of the reactants was in excess.  So the first thing that needs to be done is a balanced equation needs to be written.

3Mg(s) + N2(g) -> Mg3N2(s)

With the product calculated, you can figure out the percent composition of Magnesium and Nitrogen from the molecular formula as the percent composition will be the same whether twenty grams or twenty kilograms of product were made.  
"A real fart is beefy, has a density greater than or equal to the air surrounding it, consists

Sponsored Links