Replacement Reactions Lab

Conclusion Questions:

Part I

1. What type of chemical reaction occurred?
     Single Replacement

2. What is the solid formed in the reaction?'
     Copper Nitrate

3. Would the reaction still occur if we used aluminum wire instead of copper? Why or Why not?

     Yes, because it would still be the same type of reaction that would occur.

Part II

4. Which of the metals reacted the fastest? The slowest?
     Magnesium was the fastest reaction and tin was the slowest.

5. Based on your observations, rank the metals, including copper, from most active to least. Does this agree with the activity series chart on your reference tables?
     Most active --> least active: Magnesium, Aluminum, Zinc, Tin, Copper


Part III

6. Why did you have to expose the inside of your penny by filing it?
     Filing the edges was the only way to expose the zinc inside of the penny to the HCl.

7. Calculate the percentage of copper in your penny:
     19.7% ≈ 20%

8. Find the percent error in the amount of copper you calculated for your penny, using the known percent of copper you looked up in the pre-lab.
     17.2% ≈ 17%

9. Where might any error have come from, aside from human or instrument error? Be specific.
     We may not have let the penny sit long enough in the HCl (Hydrochloric Acid) to let the zinc fully dissolve away, which left some behind, causing the greater percentage of copper.



10. When acid is added to the penny, bubbles appear. According to your balanced equation, what type of gas do you think is released from the reaction?
     Hydrogen gas is released through the bubbles.

Type of Chemical Reactions Lab

Observations:
Sample	Before rxn	After rxn
A: Cu	The wire was light brown, skinny, and shiny.	The flame was green and orange. The copper began melting and turned bright orange. A piece fell off and turned black. .
Mg	The ribbon had a silver color, wasflat and somewhat bent	Once the ribbon got hot enough, it burst into an intensely bright, white flame. After cooling, a white powdery substance was left on the prongs where the ribbon was.
B: CuCO4	It was a light green, powdery chalk-like substance.	As the Copper(II) Carbonate got hotter, it slowly started to turn all black. When it was all black and the burner was turned off, we put the lit splint in the test tube and the flame went out. The smoke dipped to the bottom and back up and out the top.
C: Zn + HCl	The Zinc was like a small grey   rock. The liquid was clear/ transparent.	Once the Zinc was dropped into the Hydrochloric Acid, the acid started to bubble immensely and steam /smoke was coming out of the top of the tube. We put the lit splint in the test tube and the flame went out with a pop.
Zn + CuSO4	The Zinc was like a small grey   rock. The liquid was light blue, somewhat clear/transparent.	Very little reaction. The Zinc gets darker in color.
D: Pb(N03)2 + Kl	The lead nitrate and the potassium iodide were clear/transparent liquids.	Once the potassium iodide is added to the lead nitrate, the liquid turned entirely yellow. After it set, the yellow stayed at the bottom.

Questions and Problems:

I.

            A) Copper(I) + Oxygen à Copper Oxide                 

                 Solid + Gas à Solid

                        2Cu + O₂ à 2CuO

           

B) Magnesium + Oxygen à Magnesium Oxide

     Solid + Gas à Solid

                        2Mg + O₂ à 2MgO

C) Copper(II) Carbonate à Copper Oxide  + Carbon Dioxide

     Solid + Solid à Gas

                        CuCO₃ à CuO + CO₂

D) Zinc + Hyrdochloric Acid à Zinc Chloride + Hydrogen

     Solid + Aqueous à Aqueous + Gas

                        Zn + 2HCl à ZnCl₂ + H₂

E) Zinc + Copper(I) Sulfate à Zinc Sulfate + Copper(I)

     Solid + Aqueous à Aqueous + Solid

                        Zn + CuSO₄ à ZnSO₄ + Cu

F) Lead(II) Nitrate + Potassium Iodide à Potassium Nitrate + Lead Iodide

    Aqueous + Aqueous à Aqueous + Solid

                        Pb(NO₃)₂ + 2KI à 2KNO₃ + PbI₂

II.

A) We took a wood splint and lit the end on fire and placed it over the end of the test tube, and the flame went out. The carbon dioxide in the tube displaced the oxygen needed to make the fire burn, thus putting out the flame.

B) We tilted the test tube and then lit a wood splint on fire and placed it over the end of the tube, and the flame went out with a pop noise.  Zn + HCl à ZnCl + H

III.

A)     Single Replacement

2AgNO₃ + Cu à Cu(NO₃)₂ + 2Ag

B)     Double Replacement

BaCl₂ + Na₂SO₄ à BaSO₄ + 2NaCl

C)     Single Replacement

Cl₂ + 2NaBr à 2NaCl + Br₂

D)     Decomposition

2KClO₃ à 2KCl + 3O₂

E)      Regular Combustion

2H₂ + O₂ à 2H₂O