The aim of this experiment is to discover which of the following equations is correct for the decomposition of CuCO3. The two equations that I am going to use are:

• Toxic to plants and fungi.
• Harmful when ingested
• Combustion hazard (as fine powder)

It is appropriate that the copper carbonate is not handled with bare skin and should wear protective gloves or use tweezers or a spatula. Safety glasses should also be worn as a solid block may easily crumble.

(Resource:http://www.wm-blythe.co.uk/WMBLYTHE/CSDS.nsf/0/6260fa2f9501f1b9802569430043246f?OpenDocument&ExpandSection=-1000)

Method

To my knowledge there are only three possible ways to set out this experiment with the available equipment. Two of these methods are similar and both use water displacement while the other uses a syringe to collect the produced gas directly.

I will attach experiment diagrams separately each properly labelled.

List of Apparatus

1 Syringe (with appropriate readings)

1 Tripod

1 Gauze

1 Boiling Tube

1 Boiling Tube Rack

1 Bung (with hole)

1 length of rubber tubing

1 Stand (With burette holder)

1 Water Bath

1 Burette

1 set of hand operated tongs

1 Bunsen burner

1 set of goggles per participant or observer

1 set of gloves (preferable)

1 Spatula/tweezers

Method 1

Fill the water bath with enough water to cover the rubber and the bottom of the measuring cylinder. Fill a measuring cylinder with water and upturn over the rubber tube with and rest in water. Take the reading from the measuring cylinder and use this reading as a reference. Use the clamp and stand to hold upright and in place.

Place 0.08g of copper carbonate in the boiling tube and place it in the rack. Attach the other end of the rubber tube to the bung and place in the boiling tube. Put the Bunsen burner under the tripod with the gauze on top. Place the test tube rack on the gauze and light the Bunsen burner. (Don’t forget to wear safety spectacles). Wait for the gas produced to displace the water. Calculate the amount of gas produced using the reference that was taken.

Method 2

Almost exactly the same as method 1 but instead of using a measuring cylinder use an upturned burette making sure that the valve is closed yet still take a reference. For this you will have to use a burette clamp as it is very fragile and may break.

Method 3

With this method there is no need for the water bath or the clamp stand. Instead you will use a syringe to measure the gas produced directly. To do this attach the rubber tubing to the bung and a syringe. Make sure that the plunger is fully compressed and that you allow the as to cool before taking a reading as the temperature will affect the results.

Chosen Method

I have chosen method 3 as my preferred method. This is because there are fewer inaccuracies using a syringe. This is because all the gas is collected in the syringe and any Carbon Dioxide may produced may not dissolve in the water bath. It can also be more accurate as there are a variety of syringe sizes all with different markings. This makes it easier to find a suitable syringe for the collection of the gas.

Calculations

Equation 1

The relative molecular mass of 1 mole of Copper Carbonate (Mr) is:

Mr = 64 + 12 + 48

Mr = 124

However the equation specifies that 2 moles of copper carbonate are used therefore the Mr of copper carbonate for the equation is 248g.

2 moles of Carbon Dioxide are also used therefore the Mr = (12 + 32)*2

                                                                                        Mr = 88g

½ a mole of Oxygen is used in this equation therefore Mr = 32/2

                                                                                       Mr = 16g

By using the equations n=V/24 and n=m/Mr I can calculate the amount of gas that would be produced by each equation.

By using 0.16g (if I used too much copper carbonate too much gas would be produced to collect easily) of copper carbonate I predict that for this equation 0.018dm³ of as would be produced.

Total amount of gas is 104g.

I calculated this by:

n= m / Mr

n= 0.16 / 248

n= 6.45*10^-4 moles

Because 2.5 moles of gas are produced I will multiply the number of moles by 1.25.

V= n*24

V= [(6.45*10^-4)*1.25] * 24

V= 0.019dm³

Equation 2

In this Equation only 1 mole of copper carbonate is used to produce 1 mole of Carbon Dioxide, so Mr1 = 124 and Mr2 = 44.

By using the same amount of Copper carbonate I can predict that 0.0432dm³ of gas will be produced.

Because only Carbon Dioxide is produced the total amount of gas is 44g.

I calculated this by:

n= m / Mr

n= 0.16 / 124

n= 1.29*10^-3 moles

V= n*24

V= 1.29*10^-3*24

V= 0.031dm³

If my equations are correct I will either collect 19 or 31 cm³ of gas. This tells me which equation is correct.

Errors in Procedure

There are several procedure errors that can occur. I will state and suggest ways to improve two of them.

1. There could be some compression of the gas in the syringe. This could be solved by allowing the gas to be cooled before taking the reading. This is because the gas expands when it is given energy.

2. The other error is that Carbon Dioxide can dissolve in water, and is also heavier than oxygen. The as produced could be lost in the water or the pressure created by the gases weight may affect the readings in the measuring cylinder and burette.

Errors in Measurement

There may also be errors in measurement because of the accuracy of the devices used.

1. A measuring cylinder does not have very many markings on it and they are spaced further apart than required. This makes it more difficult to estimate in between markings and may affect your results.

2. The scales used to weigh the mass of the Copper carbonate may not be accurate enough as a mass of 2d.p. is required and most available scales read no more than 2d.p. as 3d.p. is more preferable.

Method Diagrams