SCH3U U1 Experiment #10 DecompositionReactions
Purpose:
To observe four decompositionreactions.
Hypothesis:
Part A:
Lead (II) Nitrate > Lead +Nitrogen Gas + Oxygen Gas
Part B:
Hydrogen Peroxide > Water + OxygenGas
Part C:
Ammonium Carbonate > Ammonia +Carbon Dioxide
Part D:
Copper (II) Carbonate > CopperOxide + Carbon Dioxide
Materials:
See experiment handout. U1 Experiment#10 Decomposition Reactions
Procedure:
See experiment handout. U1 Experiment#10 Decomposition Reactions
Part D: (teacherdemonstration)
1)Heat a small amount of CopperCarbonate in a test tube over a Bunsen burner.
2)Collect the gas produced and bubblethrough lime water.
Observations:
PartA:
Lead (II) Nitrate --pale yellow finedull powder
Glowing splint test-- reignited
Burning splint test-- brightened
--brown gas was produced (NitrogenDioxide)
Part B:
Hydrogen Peroxide-- clear, colorlessliquid
Magnesium (IV) Oxide-- fine blackpowder
Flaming splint test-- wasextinguished
Glowing splint test-- reignitessplint
Reaction: reacts vigorouslyproducing a gas, dark powder mixed throughout. Reaction continuedfor several minutes.
Part C:
Ammonium Carbonate-- fine dull whitepowder
Red litmus-- turned blue
Blue litmus-- stayed blue
Dried cobalt paper-- turned pink
Glowing splint test--extinguished
Burning splint test--extinguished
Part D:
Copper Carbonate-- dull green-bluefine powder
Lime water-- clear liquid
Results of lime water test: Limewater turned cloudy and milky, and a precipitate formed in limewater.
CuCO3 turns black as thereaction occurs.
Conclusion:
Four decompositions reactions wereobserved. In all of the experiments gases were produced.
Discussion:
1)The balanced equations are:
Part A:
2Pb(NO3)2 >4NO2 + 2PbO + O2
Part B:
H2O2 >H2 + O2
Part C:
(NH4)2CO3 > 2NH3 +CO2 + H2O
Part D:
CuCO3 > CO2+ CuO
2) The gas produced though thedecomposition of compounds containing the carbonate ion is carbondioxide (CO2).
3) There are many tests to confirmthe presence of different gases. To test for CO2 you canbubble the gas through lime water and it should turn cloudy ormilky. To test for O2 you can place a glowing splint inthe gas and it should ignite. The presence of NH3 can beconfirmed by it's ability to extinguish a glowing or flamingsplint, also it turns red litmus paper blue, and has a distinctivepungent odor. The presence of water vapor can be confirmed withcobalt paper, which turns pink when contacted by water vapor.Hydrogen gas (H2) is tested for by placing a flamingsplint in the unknown gas, and a popping sound will be heard, thesplint will also be extinguished.
4) A balanced chemical equation forammonium gas and water is:
NH3 + H2O >NH4+(aq) +OH-(aq)
This explains why NH3causes red litmus paper to turn blue, as the products areNH4+ + OH- , and OH- isan indicator of a base, and bases turn red litmus paper blue. Thishappens because as the ammonium gas contacts the moist litmus paperit reacts with the water that has moistened the paper beforeeffecting the litmus paper.
5) A balanced chemical equation forcarbon dioxide and water is:
CO2 + H2O >H2CO3(aq)
The product is carbonic acid, andacids turn moist litmus paper red. The carbon dioxide reacts withthe water held by the litmus paper before reacting with the litmuspaper so is acidic when affecting the paper.
SCH3U U1 Experiment #10 DecompositionReactions
Purpose:
To observe four decompositionreactions.
Hypothesis:
Part A:
Lead (II) Nitrate > Lead +Nitrogen Gas + Oxygen Gas
Part B:
Hydrogen Peroxide > Water + OxygenGas
Part C:
Ammonium Carbonate > Ammonia +Carbon Dioxide
Part D:
Copper (II) Carbonate > CopperOxide + Carbon Dioxide
Materials:
See experiment handout. U1 Experiment#10 Decomposition Reactions
Procedure:
See experiment handout. U1 Experiment#10 Decomposition Reactions
Part D: (teacherdemonstration)
1)Heat a small amount of CopperCarbonate in a test tube over a Bunsen burner.
2)Collect the gas produced and bubblethrough lime water.
Observations:
PartA:
Lead (II) Nitrate --pale yellow finedull powder
Glowing splint test-- reignited
Burning splint test-- brightened
--brown gas was produced (NitrogenDioxide)
Part B:
Hydrogen Peroxide-- clear, colorlessliquid
Magnesium (IV) Oxide-- fine blackpowder
Flaming splint test-- wasextinguished
Glowing splint test-- reignitessplint
Reaction: reacts vigorouslyproducing a gas, dark powder mixed throughout. Reaction continuedfor several minutes.
Part C:
Ammonium Carbonate-- fine dull whitepowder
Red litmus-- turned blue
Blue litmus-- stayed blue
Dried cobalt paper-- turned pink
Glowing splint test--extinguished
Burning splint test--extinguished
Part D:
Copper Carbonate-- dull green-bluefine powder
Lime water-- clear liquid
Results of lime water test: Limewater turned cloudy and milky, and a precipitate formed in limewater.
CuCO3 turns black as thereaction occurs.
Conclusion:
Four decompositions reactions wereobserved. In all of the experiments gases were produced.
Discussion:
1)The balanced equations are:
Part A:
2Pb(NO3)2 >4NO2 + 2PbO + O2
Part B:
H2O2 >H2 + O2
Part C:
(NH4)2CO3 > 2NH3 +CO2 + H2O
Part D:
CuCO3 > CO2+ CuO
2) The gas produced though thedecomposition of compounds containing the carbonate ion is carbondioxide (CO2).
3) There are many tests to confirmthe presence of different gases. To test for CO2 you canbubble the gas through lime water and it should turn cloudy ormilky. To test for O2 you can place a glowing splint inthe gas and it should ignite. The presence of NH3 can beconfirmed by it's ability to extinguish a glowing or flamingsplint, also it turns red litmus paper blue, and has a distinctivepungent odor. The presence of water vapor can be confirmed withcobalt paper, which turns pink when contacted by water vapor.Hydrogen gas (H2) is tested for by placing a flamingsplint in the unknown gas, and a popping sound will be heard, thesplint will also be extinguished.
4) A balanced chemical equation forammonium gas and water is:
NH3 + H2O >NH4+(aq) +OH-(aq)
This explains why NH3causes red litmus paper to turn blue, as the products areNH4+ + OH- , and OH- isan indicator of a base, and bases turn red litmus paper blue. Thishappens because as the ammonium gas contacts the moist litmus paperit reacts with the water that has moistened the paper beforeeffecting the litmus paper.
5) A balanced chemical equation forcarbon dioxide and water is:
CO2 + H2O >H2CO3(aq)
The product is carbonic acid, andacids turn moist litmus paper red. The carbon dioxide reacts withthe water held by the litmus paper before reacting with the litmuspaper so is acidic when affecting the paper.