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Pupil
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(Texas Tech University)
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posted by  Cypanther on 6/8/2008 8:41:04 PM  |  status: Closed  

Predicting the amount of reactant provided for the experiment

Course Textbook Chapter Problem
General Chemistry General Chemistry 8th edition, by Ebbing and Gammon N/A N/A
Question Details:
Sodium bicarbonate was added to an unlimited amount of sulfuric acid undergoing a reaction to produce sodum sulfate plus carbonic acid← (which turned it water vappor and carbon dioxide upon heating)
 
The experimental yield for sodium sulfate was 2.25 grams. You are to predict the amount of sodium bicarbonate used in the reaction. Upon verification from the instructor, the actual mass of the sodum bicarbonate used was 3.75 grams. Determine the % error.
 
I know that the experimental value for mass of NaHCO3 is 2.66g I'm having trouble predicting the amount of reactant provided for the experiment. I am told from the earlier part of this equation that the mass of NaHCO3 is 2.095 grams.
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Sage
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posted by SamiLiLOnE on 6/8/2008 10:20:22 PM  |  status: Live
Asker's Rating: Lifesaver   
Cypanther's comment:
"I completely understand where the 3.75 plays a part"
Response Details:
2 NaHCO3 + H2SO4 --> Na2SO4 + 2 H2CO3

2.25 g Na2SO4 x mol Na2SO4 x 2 mol NaHCO3 x 84 g NaHCO3 = 2.66 g NaHCO3 used
                               142 g            1 mol Na2SO4     mol NaHCO3

To find the percent error, use the actual mass used (3.75 g) to find how much sodium sulfate should have been yielded.
3.75 g NaHCO3 x mol NaHCO3 x 1 mol Na2SO4 x 142 g Na2SO4 = 3.17 g Na2SO4
                                   84 g            2 mol NaHCO3    mol Na2SO4

% error = 3.17 - 2.25 = 0.29 = 29%
                     3.17

So the answer you got is correct. That is the amount that is required to react in order to produce 2.25 g Na2SO4


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