Experiment_604_Thermal_Decomposition_of_Sodium_Bicarbonate_1_2_3
- Page ID
- 302987
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Laboratory Date: Date Report Submitted: |
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Student ID |
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Experiment Number and Title |
Experiment 604: Thermal Decomposition of Sodium Bicarbonate |
Experiment 604: Thermal Decomposition of Sodium Bicarbonate
Section 1: Purpose and Summary
Determine if sodium bicarbonate decomposes by reaction A or reaction B when heated.
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NaHCO3(s)→Na2CO3(s)+H2O(g)+CO2(g) |
Reaction A |
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Sodium bicarbonate |
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Sodium carbonate |
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Water vapor |
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Carbon dioxide |
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NaHCO3(s)→Na2O(s)+H2O(g)+CO2(g) |
Reaction B |
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sodium bicarbonate |
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Sodium oxide |
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Water vapor |
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Carbon dioxide |
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NaHCO3 is commonly called sodium bicarbonate. When NaHCO3 is heated above 110 °C, H2O and CO2 are produced by a chemical change. After the decomposition reaction is complete, a white solid residue remains. Among all possible reactions, the two possibilities listed above are most likely to explain these observations.
Students are to choose between reactions (A) and (B) on the basis of their laboratory work, which will involve heating a weighed sample of sodium bicarbonate in a crucible and weighing the residue left in the crucible after heating. From the mass of the solid product ("residue"), students should be able to decide if it is Na2CO3 or Na2O.
Section 2: Safety Precautions and Waste Disposal
Safety Precautions:
Wear your safety goggles.
Do not attempt to move a hot crucible; allow sufficient time for it to cool.
Use care when handling HCl solutions. If any HCl splashes on your skin or clothing, rinse it off immediately with plenty of water.
Waste Disposal:
The solid waste may be discarded in one of the regular garbage cans.
Section 3: Procedure
Part 1: Clean and Weigh Crucible
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Part 2: Measure Mass of Residue after Heating
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Part 3: Data Table
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Before heating |
After first heating |
After second heating |
After third heating |
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Mass of crucible, lid & sample (g) |
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Mass of crucible & lid (g) |
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Mass of sample (g) |
Part 4: Test for Presence of Carbonate
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Carbonate salts such as Na2CO3 react with acids to form CO2 gas. If the solid fizzes when some HCl solution is added to it, this indicates that the solid is a carbonate or bicarbonate. Fizzing will not be observed if the product is Na2O. Add a few drops of 6 M hydrochloric acid to the solid product in your crucible to double-check your results. Record your observations. |
Observations: |
Section 4: Calculations
Part 1: Balance Chemical Equations
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Before attempting the calculations, balance the chemical equations for reactions A and B below. |
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____NaHCO3(s)→____Na2CO3(s)+____H2O(g)+____CO2(g)
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Reaction A |
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Reactants Na atoms: _______ C atoms: _______ H atoms: _______ O atoms: _______
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Products Na atoms: _______ C atoms: _______ H atoms: _______ O atoms: _______
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____NaHCO3(s)→____Na2O(s)+____H2O(g)+____CO2(g)
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Reaction B |
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Reactants Na atoms: _______ C atoms: _______ H atoms: _______ O atoms: _______
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Products Na atoms: _______ C atoms: _______ H atoms: _______ O atoms: _______
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Part 2: Yield Calculations
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Theoretical yield of Na2CO3:
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Theoretical yield of Na2O:
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% _____ yield= \(\frac{\text {actual yield}}{\text {theoretical yield}}\) ×100
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Percent yield of Na2CO3:
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Post Lab Questions:
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Notes: