An excess of methane reacts with 10.5 g of oxygen gas, O2 in the following reaction.
CH4(g)+2O2(g)→CO2(g)+2H2O(g)
(a) Calculate the mass of carbon dioxide gas, CO2 produced and
(b) the percentage yield if only 3.8 g of CO2 is actually isolated.
CH4(g) + 2O2(g) → CO2(g) + 2H2O(g)
mols O2 = g/molar mass = 10.5/32 = estimated 0.3
Convert mols O2 mols CO2 using the coefficients in the balanced equation like this. 0.3 mols O2 x (1 mols CO2/2 mols O2) = estimated 0.3/2 or about 0.15
Then grams CO2 = mols CO2 x molar mass CO2 = 0.15 x 44 = about 7 but you need to redo all the calculations. This is the theoreticfal yield (TY).
b. The actual yield (AY) is 3.8 g.
%yield = (AY/TY)*100 = ?
To calculate the mass of carbon dioxide gas, CO2 produced, we need to use stoichiometry.
(a) First, we need to find the amount (in moles) of methane, CH4, that reacts. The molar mass of methane is 16.04 g/mol. Therefore, the number of moles of methane can be calculated as follows:
Number of moles of CH4 = mass of CH4 / molar mass of CH4
Number of moles of CH4 = (mass of CH4) / (16.04 g/mol)
Substituting the given mass of methane,
Number of moles of CH4 = 10.5 g / 16.04 g/mol
Next, we need to use the stoichiometry of the chemical reaction to find the amount (in moles) of carbon dioxide, CO2, produced. According to the balanced equation, 1 mole of methane reacts to produce 1 mole of carbon dioxide. Therefore, the number of moles of carbon dioxide can be calculated as follows:
Number of moles of CO2 = Number of moles of CH4
So, the mass of carbon dioxide produced can be calculated by multiplying the number of moles of CO2 by its molar mass, which is 44.01 g/mol.
Mass of CO2 = Number of moles of CO2 * molar mass of CO2
(b) To calculate the percentage yield, we need the actual yield and theoretical yield. Theoretical yield is the amount of CO2 that should be produced based on stoichiometry. In this case, it is the mass of CO2 calculated in part (a). Actual yield is the amount of CO2 that is actually isolated, given as 3.8 g.
Percentage yield = (actual yield / theoretical yield) * 100%
Therefore,
Percentage yield = (3.8 g / mass of CO2) * 100%