Question

When carbon is burned in air, it reacts with oxygen to form carbon dioxide. When 25.2g of carbon were burned in the presence of 78.0g of oxygen, 10.8g of oxygen remained unreacted. What mass of carbon dioxide was produced?

Answer 1

Thus, oxygen must the the limiting reagent.
C + O2 ==> CO2
78.0 g O2 to start
remaining is 10.8; therefore,
78.0-10.8 = 67.2 g oxygen consumed.
That is 67.2/32 = ?moles.
?mols O2 x (1 mole CO2/1 mole O2) = ?moles CO2.
grams CO2 = moles CO2 x molar mass CO2.

Answer 2

92.4gCO2