1st step.
Figure out the limiting reagent.
Calculate moles (mass/molar mass).
moles of sodium bicarbonate = 1/84 = 0.0119
moles of citric acid = 1/192 = 0.0052
2nd step. Divide moles by the coefficient in the
equation to see which is limiting:
Sodium bicarbonate: 0.0119/3 = 0.0040
Citric acid: 0.0052/1 = 0.0052
Based on these conclusions, sodium bicarbonate is the
limiting reagent.
Since the coefficients of sodium bicarbonate and CO2 are the
same in the equation, the number of moles of sodium bicarbonate consumed equals
the number of moles of CO2 produced. Therefore 0.0119 moles of CO2 are
produced, which is 0.524 g (after multiplying by molar mass).
Given: 3 moles of sodium bicarbonate
react with 1 mole of citric acid.
It means you have a third as many moles of
citric acid as sodium bicarbonate, which in this case is 0.119/3 = 0.0040
moles. However, we know from above that there were 0.0052 moles to begin with.
Therefore, after the reaction, there are 0.0052-0.0040=0.0012 moles of citric
acid remaining. Multiplying by the molar mass of citric acid, we get 0.238 g
remaining.
