Question

how many liters of carbon dioxide are produced at STP when 295g or propane gas (C3H8) is reacted with excess oxygen? the other product is water vapor. write out balanced equation and then all calculation for credit.

Answer 1

The balanced equation is: C3H8 + 5 O2 = 3 CO2 + 4 H2O

1) first step is to determine the molar mass you have to consult the periodic table and see the atomic mass of each element. If the element is repeated, for example 3 times, you multiple the atomic mass per 3.
C3H8= 12 x 3 + 1*8
= 44 g/mol

2)convert grams to moles so that everything will be in same unit.
moles are calculated by dividing mass by molar mass.
moles of C3H8= 295g / 44 g/mol
= 6.705 mol

3)By looking at the balanced equation, you can see that 1 mol of C3H8 will produce 3 moles of CO2. So if you have 6,705 moles, you will  obtain x moles of CO2:
1 C3H8--------3 CO2
6,705----------x  of CO2
x= 20,115 mol of CO2

4) At STP(Standard Temperature and Pressure) 1 mole of gas is equivalent to 22.4 liters.
1 mol of CO2-----22,4
20,115 -------------x liters
x= 20,115 x 22,4 =
450,6 liters.