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Chemistry Forums for Students => High School Chemistry Forum => Topic started by: Maradona on September 20, 2005, 07:41:33 PM

Title: limiting reactant
Post by: Maradona on September 20, 2005, 07:41:33 PM

ok.. i havent been paying attention in class so im a little slow.. but i have a test tommrow, i want to master fundamentals first, so is this right?

using CO + O2 --> CO2, if you started with 120 grams of Carbon monoxide and 100 grams of Oxygen gas, which reactant would run out first?? i did

120g CO ( 1 mol CO/28g CO) ( 1mol CO2/1mol CO) ( 40g CO2/1 mole CO2) = 171.4

100g O2 ( 1mol o2/32g o2)  (1mol co2/1 mol o2) (40 g CO2/1mol O2) = 125

So O2 is the limiting reactant, is this right?

Title: Re:limiting reactant
Post by: mike on September 20, 2005, 08:16:34 PM

n=m/M

n = number of moles
m = mass
M = molecular weight

CO
m = 120g
M = 28 g.mol-1
so, n = 4.3 mol

O2
m = 100g
M = 32 g.mol-1
so, n = 3.1 mol

So yes O2 is the limiting reagent

Title: Re:limiting reactant
Post by: xiankai on September 20, 2005, 08:38:44 PM

u forgot to balance the equation.

Title: Re:limiting reactant
Post by: mike on September 20, 2005, 08:42:16 PM

oops  :-[

xiankai is right, before doing what I did you have to balance the equation, sorry!