Question

2. (20 pts) Match the chemical equation with reaction type:

    Single Displacement, Double Displacement, Combination (Synthesis), or Decomposition.

Cu(NO₃)₂(aq) + 2NaOH(aq) à Cu(OH)₂(s) + 2NaNO₃(aq)     ______________________________

Cu(OH)₂(s) à CuO(s) + H₂O(g)                                                  ______________________________   

CuO(s) + H₂SO₄(aq) à CuSO₄(aq) + H₂O(l)                             ______________________________

CuSO₄(aq) + Mg(s) à Cu(s) + MgSO₄(aq)                                ______________________________

Mg(s) + H₂SO₄(aq) à H₂(g) + MgSO₄(aq)                                  ______________________________

3. (20 pts) What mass of Cu metal is required to react with 5.5 drops of 16M HNO₃?

    Assume 20 drops = 1 mL. Cu (MM 63.54 g/mol), (16M = 16 mol/L)

    Cu(s) + 4HNO₃(aq) à Cu(NO₃)₂(aq) + 2NO₂(g) + 2H₂O(l)

Show entire calculation. Box in answer. Give answer to 2 significant figures. Include unit.

5. (20 pts) One of the steps is performed in the fume hood because of the evolution of a toxic

    brown gas, nitrogen dioxide. This is during formation of ___________________________.

    Include the correct formula of the product in the copper experiment.

Answer 1

Cu(NO3)2(aq) + 2NaOH(aq) → Cu(OH)2(s) + 2NaNO3(aq) Double Replacement

Cu(OH)2(s) → CuO(s) + H2O(g)   Decomposition

CuO(s) + H2SO4(aq) → CuSO4(aq) + H2O(l) Double Replacement

CuSO4(aq) + Mg(s) → Cu(s) + MgSO4(aq) Single Replacement (redox)

Mg(s) + H2SO4(aq) →  H2(g) + MgSO4(aq) Single Replacement (redox)

2. Cu + 4 HNO3 → Cu(NO3)2 + 2 H2O + 2 NO2

5.5 drop X (1 mL/20 drop) X (1 L/1000 mL) X 16 mol HNO3/L = 0.0044 mol HNO3
0.0044 mol HNO3 X (1 mol Cu/4 mol HNO3) X 63.55 g Cu/mol = 0.0699 g Cu

3Ans.Cu(s) + 4 HNO3 (aq) →  Cu(NO3 )2 (aq) + 2 H2O(l) + 2 NO2 (g)

1. Weigh a clean, dry evaporating dish accurately. Record the mass on your Report Sheet.

2. Obtain a piece of copper wire. Place the copper into the evaporating dish and weigh the copper plus evaporating dish accurately, recording the mass on your Report Sheet.

3. Transfer the copper wire to a labeled (with your name or initials) 250 mL beaker and place it under the FUME HOOD. Your instructor will put on a pair of rubber gloves and carefully add 4.0 mL of concentrated (16 M) nitric acid, HNO3 , solution to your copper. Swirl the solution to remove the brown NO2 gas. Record your observations on your Report Sheet. (Include identities of all of the solutes in the solution.)

4. After the copper has dissolved, carefully (slowly!) add approximately 100 mL deionized water to your copper solution to dilute it. (Note: You are adding water to acid!)

NITROGEN DIOXIDE GAS: DANGER! POISON! CORROSIVE! Highly toxic by inhalation. Inhalation may be fatal. Causes severe eye damage.Contact lenses lenses should not be worn if you may be exposed to nitrogen dioxide