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The fizz produced when a tablet of Alka-Seltzer dissolves in H2O comes from the reaction of sodium carbonate,, NaHCO3, and citric acid, C6H8O7:. 3NaHCO3+C6H8O7--> 3CO2+3H2O+Na3C6H5O7. supposed the tablet containing 1.00g of sodium bicarbonate and 1.00g of citric acid reacts to completion. How many grams of CO2 are produced and how many grams of the excess reagent remain when the reaction is complete?

Verified Answer :

meerkat18

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.

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