Assuming that the volumes of carbon diox-

ide and of propane are measured under the
same experimental conditions, what volume
of carbon dioxide is produced by the complete
combustion of 20 L of propane?

i just don't understand

This is just another stoichiometry problem but since everything is a gas and measured at the same conditions, it allows us to use a shortcut.

C3H8 + 5O2 ==> 3CO2 + 4H2O

We may use volume in liters as if L = mols. Simply convert L C3H8 to L CO2 using the coefficients in the balanced equation.
20 L C3H8 x (3 mol CO2/1 mol C3H8)= 20 x (3/1) = 60 L CO2.

To find out the volume of carbon dioxide produced by the complete combustion of propane, we need to understand the balanced chemical equation for the combustion reaction. The balanced equation is:

C3H8 + 5O2 -> 3CO2 + 4H2O

This equation tells us that for every 1 mole of propane (C3H8) that reacts, 3 moles of carbon dioxide (CO2) are produced.

Now, we can use the concept of stoichiometry to calculate the volume of carbon dioxide produced. Stoichiometry is the calculation of reactants and products in chemical reactions based on balanced chemical equations.

Given that we have 20 L of propane, we need to convert it to moles using the molar volume of propane (22.4 L/mol).

20 L C3H8 x (1 mol C3H8 / 22.4 L C3H8) = 0.8928 mol C3H8

Since the stoichiometric ratio between propane and carbon dioxide is 1:3, we can calculate the moles of carbon dioxide produced by multiplying the moles of propane by the stoichiometric ratio.

0.8928 mol C3H8 x (3 mol CO2 / 1 mol C3H8) = 2.6784 mol CO2

Finally, we need to convert the moles of carbon dioxide to volume using the molar volume of carbon dioxide (22.4 L/mol).

2.6784 mol CO2 x (22.4 L CO2 / 1 mol CO2) = 59.94496 L CO2

Therefore, the volume of carbon dioxide produced by the complete combustion of 20 L of propane is approximately 59.945 L.