VARIABLES
There are several variables which could affect the outcome of this investigation. In order to make it a fair test we will attempt to keep all these variables constant except the ones we are testing (copper carbonate)
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Amount Of Metal Carbonate :
The more metal carbonate there is taking part in the decomposition, the more decomposition will take place, because there are more carbonate molecules available to join with oxygen atoms in the air, so producing more carbon dioxide. We will take raughly 0.4 g of copper carbonate to fit the total volume of gas syringe. If I use alot of the metal carbonate, it might cause an explosion because the excess gas in the gas syringe will push the burg from boiling tube.This is the result of my preliminary test.
Obviously we won’t need to control this variable because we will need all the metal to decompose. So as long as the metal in the boiling tube is still green, we will burn it until all thr metal is turned black.
This variable is one of the most impotant variable in this experiment becouse it will help to work out the mass of carbon doixide formed (by stoechiometric). “The volume of air in the gas syringe should be on zero or recorded before starting the test.)
PREDICTION
Based on my background and the preliminary experiment done, I predict that, the metal form will be copper oxide and carbon dioxide will be the gas released, Because the preliminary test gave me a black product and the gas released turn lime water 'milky,' using the reaction:
calcium hydroxide + carbon dioxide calcium carbonate + water
Ca(OH)2(aq) + CO2(g) CaCO3(s) + H2O(l).
Also from my knowlage, I know that in a reaction ,nothing is lost ,nothing is gained everything get transformed so the mass of copper carbonate should be equals the total mass of the copper oxide and carbon dioxide.
APPARATUS
- Gas Syringe
- Bunsen Burner
- Heat Mat
- 2 Clamp Stands
- Boiling Tubes
- Bung & Piping
- Bigital balance
- Spatula
- pouder of copper carbonate
- weight bohle
- goggle
- lab coat
DIAGRAM
METHOD
step 1:
Firstly, I set up the clamp stands, gas syringe and bunsen burner as shown in the diagram.
Step 2:
Using a digital balance, weight the tong and record it mass (T) it and add with accuracy 0.4 g of metal carbonate.
Step 3:
Pour the pouder in the boiling tube making sure that there is no rest in the weight bohle or minimase lost of the pouder as possible as it is.
Step 4:
Connect the boiling tube and the gas syringe with bung &piping then hold both the syringe and the boiling tube with the clamp stands
Step 5· Turn on the gas and light the Bunsen burner. burn until all the metal is turned black
Step 6:
Check when the volume of gas releaved stop increase turn thefire off and record the volume of gas this volume should be accurately recorded to minimise reading errors.
Step 7: remove the burg from the boiling tube after cooling it, weight the remaining black product. This mass is very important because it will also help me to find if the mass of copper carbonate equals mass of the two products formed.
- Repeat three time the experiment for more accuracy.
- Record all results in a suitable table
PRELIMINARY TEST RESULTS
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Initial volume of gas in the gas syringe: 0.01 dm3
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Final volume of gas in the gas syringe : 62 dm3
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The theoretical volume of gas produced in the experiment 0.061 dm3
- Mass of copper carbonate: 0.40 g
- Theorical mass of copper oxide: 0.30 g
calculations
balanced equation for the decomposition reaction.
CuCO3(s) CuO(s) + CO2(g)
By steochiometric,the ratio of mole is: 1:1:1
If n1, n2, and n3 are respectively the number of mole of CuCO3 , CuO and CO2 we have n1= n2, = n3.
Number of mole of CuCO3
n1= 0.4 : 124
n1 = 0.00322 mol
Expected volume of CO2
V3 = n1 x 24
V3 = 0.00322 x 24
V3 = 0.07728 dm3
Expected mass of copper oxide
80 x 0.4
m2=
124
m2 = 0.258g
Difference of masses 0.30 - 0.258 = 0.042g
Difference of volumes 0.061 – 0.077 = - 0.016 dm3
we expected 0.258g of copper oxide but we collected 0.30g this give:
0.30 - 0.258 = 0.042g which is 0.042 more than we expected the reason of this might be the fact that all the copper carbonate did’t burned or I did’t weight the black pouder of copper carbonate accurately.i might have other pouder on the balance.i might have done calculation errors when rounding my results.
We also expected 0.077 dm3 of CO2 but we collected 0.061dm3 that is a lost of 0.016 dm3 that could have been the causes of this I think the causes of this might be
- reading of the volume on the gas syringe
- the piping and burg might not been well cannected to the syringe and the boiling tube so I might lost some gas that way
- I might have done some calculation errors
The aim of this experiment was to determine which equation is right. My preliminary experiment shown me that it was the equation 1
But to finaly decide this I have to check if the mass of CuCO3 equals the sum of mass of (CO2 and CuO)
m1 = 0.4g
m2 =0.258g
V1 m V1 m1
n3 = = =
Vo Mco2 Vo Mco2
V1 x Mco2
So m1 =
Vo
0.077 x 44
m1 = = 0.141g
24
CONCLUSION
m1 + m2 = 0.141g+ 0.258g = 0.399g this is slightly 40, which is the mass of CuCO3 used. so my prediction was right the mass of the reactant equals the sum of product. The correct Equation is CuCO3(s) CuO(s) + CO2(g).
RISK ASSESSEMENT
To make sure that this investigation is a safe one the following safety procedures have to be followed.
· When the Bunsen burner is not being used it should be put on a yellow flame. This is the safety flame and is visible and cooler
· If a test tube cracks or melts turn off the Bunsen burner and stop the investigation immediately.
· Always wear safety goggles.
· If you can smell gas turn all of the gas taps off immediately.
· Pull the delivery tube out of the cylinder before you stop heating.
. Wear a lab coat, as copper carbonate is corrosive
. Avoid contact between the delivery tube, which is made of rubber and fire, as smoke of burning rubber might be suffocant.
BIBLIOGRAPHY
Web sites:
: chemistry: heating metal carbonate
