Copper Lab Reactions

1
Copper Lab Reactions

• Using Observational Clues
• To Predict Products

2
Step 1a

• Copper turns black when heated strongly in air.
• Cu(s) O2(g) ? CuO(s)
• black
• Redox (oxidation)

3
Step 1b

• Adding dilute H2SO4 solution to the black product
  dissolves the black product off the surface of
  the Cu, leaving behind the reddish Cu we started
  with.
• The solution containing the dissolved product is
  clear blue.
• CuO(s) H2SO4(aq) ? CuSO4(aq) H2O(l)
• blue
• Double Displacement (acid-base)

4
Step 1c

• When NaOH solution is added to the CuSO4 solution
  from 1b, a blue gel precipitate forms.
• CuSO4(aq)NaOH(aq)?Cu(OH)2(s)Na2SO4(aq)
• blue gel ppt
• Double displacement (precipitation)

5
Step 1d

• When H2SO4 solution is added to the blue gel, the
  gel dissolves and we get back a blue solution.
• Cu(OH)2(s)H2SO4(aq)?CuSO4(aq)H2O(l)
  blue soln
• Double Displacement (acid-base)

6
Step 1e

• When the blue gel is heated, we get a solid black
  product.
• Cu(OH)2(s) ?CuO(s) H2O(l)
• blue gel black solid
• Redox -- decomposition

7
Step 2a

• When blue CuSO45H2O crystals are heated, they
  turn white. Clear white liquid droplets form at
  the top of the tube.
• CuSO45H2O(s) ? CuSO4(s) 5H2O(l) blue
  crystals white powder
• (not a reaction type that weve studied. Not
  redox/decomposition, since electrons arent
  transferred between atoms)

8
Step 2b

• When water is added to the white powder from 1b,
  we get back the blue crystals we started with.
  Addition of even more water gives us our familiar
  blue solution.
• CuSO4(s) 5H2O(l) ? CuSO45H2O(s)
• CuSO45H2O(s) H2O(l) ? CuSO4(aq)
• (again, not reactions were interested in
  identifying)

9
Step 3

• When an iron nail is added to the CuSO4(aq) we
  made in 2b, the nail turns reddish in color and
  the blue color in the solution fades.
• CuSO4(aq) Fe(s) ? Cu(s) FeSO4(aq)
• blue soln reddish
• Redox single displacement

10
Step 4

• When sulfuric acid solution is added to green
  copper(II) powder, we get a gas that turns
  limewater cloudy and we get back our familiar
  blue solution.
• CuCO3(s)H2SO4(aq)?CO2(g)CuSO4(aq)H2O(l)green
  pwdr blue
  soln
• Double-Displacement - acid-base !!!

11
Step 4b

• When the green copper carbonate powder is heated,
  a gas is given off that turns limewater cloudy,
  and a black solid is left in the test tube.
• CuCO3(s) ? CuO(s) CO2(g)green pwdr black
  solid
• Redox - decomposition

12
Step 4c

• When charcoal is added to the black solid from 4b
  and the mixture is heated, a gas is given off
  that turns limewater cloudy, and reddish solid
  flecks form in the bottom of the tube.
• CuO(s) C(s) ? Cu(s) CO2(g)black
  reddish
• Redox Single Displacement