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# Stoichiometry of an Acid-Base Reaction

Procedures:

1. Take a beaker from the Glassware shelf and place it on the workbench.
***mass of empty beaker is 47.420g***
2. Take a balance from the Tools shelf and drop it directly onto the beaker. Record the mass of the empty beaker.

3. 0.5g of Na₂CO₃ to the beaker. Record the mass of the beaker plus Na₂CO₃. Remove the beaker from the balance.

4. Take a graduated cylinder from the Glassware shelf and place it on the workbench.

5. Add 5 mL of 6M HCl and 5 mL of water to the graduated cylinder.

7. Pour 1 mL of HCl solution from the graduated cylinder into the beaker, and watch for effervescence (bubbling release of CO₂ gas).

8. Open the Data window and click on the beaker. You should be able to identify one chemical compound that was not there before, meaning that it is a product of the acid-base reaction.

9. Click the Pushpin icon in the blue bar of the Data window to lock its display to the contents of the beaker.

10. Continue adding the HCl solution 1 mL at a time, until all of the Na₂CO₃ has reacted and there is no more bubbling (the Data window will also show that there is no more Na₂CO₃).

11. Take a Bunsen burner from the Tools shelf and place it on the workbench. Open the Properties window and click on the Bunsen burner. In the Properties window turn the Bunsen burner on and set it to a low flame.

12. Drag the Bunsen burner and drop it onto the beaker.

13. Heat the solution in the beaker to boiling, and continue heating until all of the liquid has boiled off leaving only solid NaCl. Remove the beaker from the burner.

14. Measure and record the mass of the beaker containing the NaCl.

Questions:

Assignment 1 of Procedure 1

1. Record and calculate the following masses:

(a) mass of empty beaker (g):

(b) mass of beaker plus Na₂CO₃ (g):

(c) Mass of Na₂CO₃ (g):

(d) mass of beaker plus NaCl (g):

(e) Mass of NaCl (g):

2. Convert the masses of Na₂CO₃ and NaCl to moles, given their molecular weights (MW) of Na₂CO₃ = 105.989 g/mole, MW of NaCl = 58.443 g/mole.

3. Calculate the experimentally determined ratio of moles of NaCl produced to moles of Na₂CO₃ reacted, according to:

mole-ratio = (moles NaCl)/(moles Na₂CO₃)

5. Use the mole ratio to write a balanced chemical equation for the reaction.

6. What is the theoretical mole ratio according to this balanced equation?

7. Use the theoretical mole ratio to calculate the theoretical yield of NaCl in grams from .5g of Na₂CO₃?

8. The "percent yield" is the ratio of the actual amount of a product to the theoretical amount. Calculate the percent yield of NaCl as:

% yield = (experimental grams NaCl) / (theoretical grams NaCl) * 100%

9. What sources of error may have reduced your yield?

#### Solution Preview

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#### Solution Summary

Stoichiometry for an acid-base reaction are discussed.

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