Question

Help!!
Can someone please show me how to set up this problem. I'm lost.

C3H8+5O2-->3CO2+4H20

If 19.2g of C3H8 and 19.2g O2 react, how many moles of CO2 can be produced?

Answer 1

This is a limiting reagent problem. You know that because BOTH reactants are given.
You have the equation.
2. Convert 19.2 g C3H8 to moles. moles = grams/molar mass.
3. Convert 19.2 g oxygen to moles. Same process.
4. Using the coefficients in the balanced equation, convert moles C3H8 to moles of CO2.
5. Same process, convert moles oxygen to moles CO2.
6. It is quite likely that the asnwer from 4 and 5 will not agree which means 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.
7. The problem ends there BUT if it had asked for grams CO2 produced you would take the smaller value and convert to grams.
g = moles CO2 x molar mass CO2.