Stoichiometry Help: NaHCO3 & CaCO3 Reactions

[Mack]

Data Table
.........NaHCO3...CaCO3
1. Mass of micro plate.....2.05g....2.05g
2. Mass of micro plate +salt...3.05g...3.05g
3. Mass of Salt .....1g.....1g
4. Moles of salt.....1/84 mol...1/100 mol
5. Mass of unreacted setup...20.66g....17.9g
6. Mass of reacted setup.....20.58g...17.85g
7. Mass of CO2 lost......08g.....05g
8. Moles of CO2 lost.....0018mol...0011 mol
9. Mass of Co2 produced as % of mass of sample 8% 5%

(reacted with vinegar)
Questions:
1. Write balanced equation for each raction.
2. From the stoichiometric relationships in the data table, find the # of moles of CO2 actually produced by each reaction.
3. How did the number of moles of CO2 actually produced by each reaction compare with the number of moles that ideally should be produced?

I don’t get how to do numbers 2 and 3. I believe I did number 2 in 8 on the chart but then what is the ideall number of moles? That’s were I am confused please help

 

[Stevedye56]

You will need to find out which reactant is limiting. Then you will need to have the balanced equation in front of you to help you with your molar ratios for the stoich. Once you have found out what substance is limiting you will know how much CO_2 is produced. Then all you need to do is convert the grams to moles and you are all set. For question #3 you need to think about experimental error. What could have gone wrong in the lab? Did you spill anything? Were your measurements accurate? Did you make sure to get all of the mass out of the reactor vessel before you took the mass on a balance? Think upon those lines.

Good Luck!
-Steve

 

[Blueshift5]

1. The balanced equation for the reaction between NaHCO3 and vinegar (acetic acid) is:
NaHCO3 + CH3COOH -> NaCH3COO + H2O + CO2

The balanced equation for the reaction between CaCO3 and vinegar is:
CaCO3 + 2CH3COOH -> Ca(CH3COO)2 + H2O + CO2

2. From the data table, we can see that the moles of CO2 lost in the reaction between NaHCO3 and vinegar is 0.0018 mol, and the moles of CO2 produced as a percentage of the mass of sample is 8%.

Similarly, for the reaction between CaCO3 and vinegar, the moles of CO2 lost is 0.0011 mol, and the moles of CO2 produced as a percentage of the mass of sample is 5%.

3. The ideal number of moles of CO2 that should be produced can be calculated using stoichiometry and the balanced equations. For the reaction between NaHCO3 and vinegar, the ideal number of moles of CO2 produced would be equal to the number of moles of NaHCO3 used in the reaction, which is 1/84 mol. Similarly, for the reaction between CaCO3 and vinegar, the ideal number of moles of CO2 produced would be equal to the number of moles of CaCO3 used in the reaction, which is 1/100 mol.

Comparing the ideal number of moles with the actual number of moles produced, we can see that there is a slight difference, with the actual number of moles being slightly higher. This could be due to experimental errors or incomplete reactions.