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Chemistry Stoichiometry Help?
The question is find the mass of carbon dioxide that will form when 2.6 g of C2H6O is burned in excess oxygen gas in the reaction. Excess oxygen means no limit to the oxygen gas. (C2H6O + O2 yields CO2 + H2O)
I already know the answer is 4.97 g but i don't understand how to get to the answer.
1 Answer
- Anonymous9 years agoFavorite Answer
Very simple style of question, once you get the method you will be able to answer any questions of this type.
FIRSTLY write a balanced equation
C2H6O + 3O2 = 2CO2 + 3H2O
SECONDLY we are already told that C2H6O is the limiting reagent and so we need to work out how many moles of this we have combusted.
Molar mass of C2H6O = 12 + 12 + 1 + 1 + 1+ 1+ 1+ 1 + 16 = 46 g/mol
n = m / MM
n = 2.6 g / 46 g/mol = 0.057 mol
THIRDLY we need to look at our balanced equation and work out the stoichiometry relationships between the limiting reagent (C2H6O) and the product in question (CO2)
C2H6O + 3O2 = 2CO2 + 3H2O
We can see that every mole of C2H6O produced 2 moles of CO2
ratio 1:2
we have reacted 0.057 moles of C2H6O so we should produced (2 x 0.057 mol) 0.114 moles of CO2
FOURTHLY we need to convert the amount of products from moles to a mass (g)
n = m/MM
MM of CO2 is 12 + 16 + 16 = 44 g/mol
m = n x MM
m = 44 g/mol x 0.114 mol = 5.02 g
so we produced 5.02 g of CO2 if we burn 2.6 g of C2H6O in excess oxygen