posted by Keith on .
The equation below shows the incomplete combustion of ethene.
C2H4(g) + 2O2(g) ==> 2CO(g) + 2H2O(g)
If 2.70 mol C2H4 is reacted with 6.30 mol O2,
a) identify the limiting reagent.
b) calculate the moles of water produced.
Show all steps.
Limiting reagent problems are pretty much alike. Print these instructions and memorize them.
1. Write and balance the equation. You have that.
2. Convert grams to moles. moles = grams/molar mass. Your problem has already done that but its a step most problems require.
3a. Using the coefficients in the balanced equation, convert moles ethene to moles of the product.
3b. Same procedure, convert moles oxygen to moles product.
3c. It is quite likely that the answer to 3a and 3b will not be the same. Obviously, one of them is wrong; the correct answer in limiting reagent problems is ALWAYS the smaller value and the reagent producing that value is the limiting reagent.
4. Now use the value from 3c to convert to grams of the product. g = moles x molar mass.