Purpose Statement: The purpose of this experiment is to determine the coefficients for the balanced equation, identify the limiting/excess reagents, and to determine the percent yield of the reactions 

Hypothesis: When the mass of the products formed in a reaction are determined, then the percent yield of the reaction can be determined by expressing the mass of the actual to the mass of the theoretical as a percent.

Variables:

IV:  Mass of limiting reagent

DV: Mass of product formed

Control: The theoretical yield of the product

Materials: CuCl2, iron nail, beakers, wash bottle, petri dish, stirring rod, test-tube, tongs graduated cylinder. 

Safety: CuCl2 is toxic, so avoid skin contact.

Summary of Procedure: 

Pre-lab Assignment:

1. Use the following data table to complete the questions below:

Items

Volume of copper (II) chloride 0.050 L

Molarity of copper (II) chloride  1.0 M

Mass of empty beaker  97.48 g

Mass of nails before reaction  17.07 g

Mass of nails after reaction  14.42 g

Mass (g) beaker and copper product  100.60 g

Theoretical Yield:

1. Write a word equation for the reaction.

Ans: copper (II) chloride (aq) + iron nails (s) → iron (II) chloride (aq) + copper (s) 

2. Write a balanced chemical equation for the reaction and classify it.

Ans: 1 CuCl2 (aq) + 1 Fe (s) → 1 FeCl2 (aq) + 1 Cu (s) 

3. Calculate the number of moles of copper (II) chloride present in the solution.   moles = M x V

Ans: moles = (1.0 M x 0.050 L) = 0.050 mol CuCl2 

4. What is the maximum number of moles of copper that can be produced from the copper(II) chloride?

Ans: 0.050 mol CuCl2 x ( 1 mol Cu / 1 mol CuCl2 ) = 0.050 mol Cu     copper chloride is the LR

5. Calculate the number of moles of iron present in the nail?                                moles = mass nail / 55.85

Ans: moles = 17.01 g Fe / 55.85 = 0.3056 mol Fe 

6. What is the maximum number of moles of copper that can be produced from the iron nail?

Ans: 0.3056 mol Fe x (1 mol Cu / 1 mol Fe ) = 0.3056 mol Cu       The nail is the XS

7. Which reagent is the limiting reagent? Explain

Ans: CuCl2 is the limiting reagent because it produces the least amount of product. 

8. Which reagent is the excess reagent? Explain

Ans: Fe is the excess because it produces the greatest amount of product. 

9. How many grams of copper can theoretically be produced from the limiting reagent?   mass  = moles x 63.55

Ans: mass = (0.050 moles) x (63.55 g / mol) = 3.17 g     Cu theoretical yield 

10. How much excess is left over? (Mass of nail at the end of the reaction)

Ans: The excess of the nail that is left over is 14.42 g

Actual Yield:

11. How many grams of copper was actually produced?   

mass Cu = (mass beaker and product) - (mass empty beaker)

Ans: 100.60 g - 97.48 g  = 3.12 g Cu 

12. How many moles of copper were actually produced?

moles Cu = mass Cu / 63.55

Ans: moles = 3.12 g / 63.55 = 0.049 mol Cu

13. How many grams of iron actually reacted? 

mass Fe = (mass of nail before - mass of nail after)

Ans: 17.07 g - 14.42 g = 2.65 g Fe 

14. How many moles of iron actually reacted? moles Fe  =  mass Fe / 55.85

Ans: moles = 2.65 g / 55.85 = 0.047  mol Fe 

15. Determine your percent yield?

percent yield  =  (actual yield / theoretical yield) x 100

Ans: % yield = 3.12 g Cu / 3.17 g Cu x 100 = 98.4% 

What is the mole ratio of copper to iron?

mole Fe / mole Cu

Ans: mole Fe / mol Cu = 0.047 / 0.049 = 0.99 = 1.0 

16.  Calculate the percent error in your value for the mole ratio. Your teacher will give you the accepted value. 

percent error = [(experimental value - accepted value) / accepted] x 100

Ans: % error = (1.0 - 1.0) / (1.0) x 100 = 0 %

17. Does your mole ratio agree with your balanced equation? Explain your answer.

Ans:  Yes my mole ratio agrees with my balanced equation because the percent error, 0 %, is less than the accepted error of 20%.

18. What happened to the iron nail that was consumed in this reaction?  

Ans: The iron underwent a single-replacement reaction in which the copper came out as a rusty brown solid and the iron went into solution (turned yellow) as ions (iron (II) chloride).