How many grams of methane should be burned in an excess of oxygen at stp to obtain 5.6 l of carbon dioxide?
2.0 g
4.0 g
16.0 g
32.0 g

The balanced chemical reaction would be as follows:

CH4 + O2 = CO2 + 2H2O

We are given the amount of CO2 product in the reaction. This will be the starting point for the calculations. We do as follows:

5.6 L CO2 ( 1 mol / 22.4L ) ( 1 mol CH4 / 1 mol CO2 ) ( 16.05 g / 1 mol ) = 4.01 g CH4 needed