1. Introduction to Chemical Reactions: Copper Cycle
1. The goal of this experiment is to review several classes of chemical reactions: and learn some synthetic chemistry techniques
2. The reactions will be performed in a specific order and, when completed, will regenerate the starting material, pure copper (Conservation of Mass)
3. You are asked to practice your observational skills by recording the changes that occur at each step of the cycle. Color changes, the generation of gases or precipitates and changes in temperature are all examples of the types of phenomena you should be looking for when studying chemical reactions.
𝑃𝑒𝑟𝑐𝑒𝑛𝑡 𝑌𝑖𝑒𝑙𝑑= 𝐶𝑜𝑝𝑝𝑒𝑟 𝑃𝑟𝑜𝑑𝑢𝑐𝑡 𝐶𝑜𝑝𝑝𝑒𝑟 𝑆𝑡𝑎𝑟𝑡𝑖𝑛𝑔 𝑀𝑎𝑡𝑒𝑟𝑖𝑎𝑙 𝑥100%
𝑃𝑒𝑟𝑐𝑒𝑛𝑡 𝑌𝑖𝑒𝑙𝑑= 𝑔 𝐶𝑢 𝑝𝑜𝑤𝑑𝑒𝑟 0.51 𝑔 𝐶𝑢 𝑤𝑖𝑟𝑒 𝑥100%=73% Yield

2. Specific Reactions
Cu(s) HNO3(aq) > Cu(NO3)2(aq) NO2(g) H2O(l)
Brown NO2(g) is quite toxic; reactions must be done in hood
Concentrated HNO3(aq) is corrosive and oxidizing; wash immediately if you get any on your skin.
Cu(NO3)2(aq) NaOH(aq) > Cu(OH)2(aq) NaNO3(aq)
Blue gelatinous copper(II) hydroxide forms
NaOH(aq) is mildly corrosive

3. Cu(OH)2(aq) + Heat --------> CuO(s) + H2O(g)
Cu(OH)2(aq) is not stable when heated and decomposes
Black CuO(s) is formed. React until no blue color is left
CuO(s) H2SO4(aq) > Cu(SO4)(aq) H2O(l)
Black CuO(s) is soluble in acid solution to form blue clear solution
6 M H2SO4(aq) is corrosive

4. Cu(SO4)aq + Zn(s) --------> Zn(SO4)aq + Cu(s)
H2SO4(aq) Zn(s) > Zn(SO4)aq H2(g)
Single replacement oxidation/reduction reaction gives us back copper
Must continue reaction until:
All blue color is gone from solution
All Zn(s) is dissolved. Excess Zn(s) will alter % Yield
Techniques
Decanting = pouring off liquid without losing solid
Washing removes byproducts [water, methanol, acetone (flammable)]
Drying evaporates solvents leaving pure, dry Copper solid

5. Incident: NaOH Clothing Damage Incident: Acid Splash on Latex Gloves