The aim of this experiment is to determine the order of the reactivity series by investigating the thermal breakdown of metal carbonates.

The formula for how a metal reacts with dilute acid is:

Metal + Acid = Metal Salt + Hydrogen

The hydrogen that is given off in the above reactions can be indentified by capturing the hydrogen in a test tube. Having done this you then place a glowing splint inside the test tube. A pop sound can be heard if hydrogen is present in the test tube.

The reactivity series was determined by how all of the metals react to the air, water and dilute acid. The most reactive metals were placed at the top of the reactivity series, the least reactive metals were placed at the bottom of the reactivity series.

Below is the reactivity series, showing the metals symbol and which group the belong to:

Potassium K 1

Sodium Na 1

Lithium Li 1

Calcium Ca 2

Magnesium Mg 2

Aluminium Al 3

Carbon C 4 (non-metal)

Zinc Z Transition Metal

Iron Fe Transition Metal

Tin Sn 4

Lead Pb 4

Hydrogen H (non-metal)

Copper Cu Transition Metal

Silver Ag Transition Metal

Gold Au Transition Metal

Platinum Pt Transition Metal

The periodic table also shows which groups the metals belong to. The enclosed periodic table displays metals and non-metals.

The metals at the top of the reactivity series have a tight bond with their carbonates. Their atoms are stable, and these atoms become more stable the higher in the reactivity series you go. Potassium and the other very reactive metals have a very tight hold on their carbonates. Their atoms are also very stable. A stable atoms has 8 electrons on its outer shell. Therefore it will be extremely hard if not impossible to break this bond the metal has with its carbonate. It will take longer to thermally decompose these metals at the top of the reactivity series, because these metal have a tight hold on their carbonate, meaning it will take a long time to break this bond. When these metals are thermally decomposed it happens vary slowly

The metals at the bottom of the reactivity series have a loose bond with their carbonates. Also their atoms aren't stable, meaning they have less than 8 electrons on their outer shell. They therefore have to either loose the electrons on the outer shell (This usually happens if there is on electron on the outer shell). The atoms can also share some of its electrons with another atom to become stable. Therefore the metals at the bottom of the reactivity series are less stable than the metals at the top of the reactivity series. If the metal is unstable its bond with the carbonate will be weak. This will make it easier to be thermally decomposed. The metal will also thermally decompose quicker, because the bond can be easily broken.

The level of water in the cylinder drops as carbon dioxide is given off. This is because the carbon in carbon dioxide displaces the hydrogen in the water because carbon is higher in the reactivity series than hydrogen.

Key Variables

The key variables involved in this experiment are independent, dependent fixed variables

The independent variable is the factor that is changed. The thing that is changed in this experiment is the type of metal carbonate used. This can also be called the input variable.

The dependent variable is the factor that is measured. In this experiment I am measuring the amount of carbon dioxide given off by the metal carbonate as it is decomposed. This is also the output variable.

The fixed variable is the factor that is kept constant. The factor that will be kept constant in this experiment is the amount of metal carbonate that is used. Also the size of the cylinder will have to kept the same and the type of test tube used. Some test tubes have thicker sides than others meaning it will take longer for the energy to be transferred to the carbonate. The size of the Bunsen burner is important because the bigger the Bunsen burner the more heat it gives off. Also the distance the Bunsen burner is from the test tube has to be kept the same, because the closer the Bunsen burner is to the test tube the quicker the metal will thermally decompose.

The carbonates that I will be testing in this investigation are:

? Iron Carbonate

? Magnesium Carbonate

? Zinc Carbonate

? Copper Carbonate

? Manganese Carbonate

I have chosen to base my investigation on these carbonates because having done my preliminary work I found out that metals above magnesium can't be thermally decomposed. Because they hold onto their carbonate too tightly.

I have chosen not to use any metals below copper because these metals will thermally decompose too quickly, because they have a very loose bond with their carbonate.

I have chosen to use Manganese because I am going to try to investigate where this fits in the reactivity series.

Also I have chosen to use 2 grams of metal carbonate each time.

Apparatus

The apparatus that will be used in this experiment is:

? Clamp Stand

? Heat Mat

? Bunsen Burner

? 10 Teat Tubes (all the same size)

? Stop Clock

? Top pan balance

? Paper

? Water Filled Trough

? Gas Cylinder

? Bung and piping

Fair Testing

To make this investigation is a fair test I will have to:

? Use the same amount of carbonate each time.

? Use the same size cylinder (250mm)

? Keep the Bunsen burner on the same flame.

? Use the same type of Bunsen burner.

? Keep the Bunsen burner at the same distance.

? Use the same size test tube

? Use a fresh test tube each time

? When measuring the mass of the carbonate, place it on paper because paper towels hold some of the carbonate.

In the experiment the diameter of the tube which takes the Co2 from the test tube to the cylinder cannot be too small. If the diameter is too small the amount of gas won't be able to travel through, creating a back pressure which will slow down the rate of the reaction.

Safety

To make sure that this investigation is a safe one the following safety procedures have to followed.

? When the Bunsen burner is not being used it should be put on a yellow flame. This is the safety flame and is visable 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 deviltry tube out of the cylinder before you stop heating.

Method

The method I will use in the investigation is as follows:

? Set up the apparatus.

? Check that all of the apparatus if working and is safe to use.

? Turn on the gas and light the Bunsen burner.

? Weight 2 grams of iron carbonate.

? Place it in the test tube.

? Fill the trough ? of the way up with water.

? Fill the cylinder to the top with water, and turn it upside down in the water filled trough.

? Place the rubber tube inside the cylinder

? Heat the carbonate, and start the stop clock at the same time as you start heating.

? Take a reading every ten seconds.

? Stop after all of the water has gone out of the cylinder.

? Repeat the experiment for iron carbonate again

? Put results in a graph and fin an average of each reading.

? Repeat for Magnesium Carbonate, Zinc Carbonate, Copper Carbonate and Manganese Carbonate.

? Put results in a table and find the averages.

? Put results onto a graph and draw a line of best fit.

Diagram

Below is a labelled diagram of the experiment:

Prediction

Using my scientific knowledge I predict that the metal that will thermally decompose the quickest will be Copper Carbonate because this is the lowest metal in the reactivity series. This means that its atoms are unstable, and that it does not have a strong hold on its carbonates. Therefore as soon as it is heated this hold copper has on its carbonate is broken and carbon dioxide given off. Copper carbonate will give off the highest volume of carbon dioxide. The carbon dioxide will displace the water in the cylinder because carbon is higher in the reactivity series than hydrogen.

My second prediction is that Magnesium Carbonate will be the hardest carbonate to thermally decompose. I predict this because Magnesium is the highest metal in the reactivity series. Using my scientific research I know that the metals near to the top of the reactivity series have a tight hold on their carbonates. Also metals at the top of the reactivity series have stable atoms. As the carbonate is heated it will longer for carbon dioxide to be given off, because the bond the Magnesium has with it carbonate is very strong. Magnesium will give off the least amount of carbon dioxide. The carbon dioxide will displace the water in the cylinder because carbon is higher in the reactivity series than hydrogen.

I cannot predict where Manganese will be in the reactivity series.

This is the order that I think the metals will decompose in. Fastest first excluding Manganese:

. Copper Carbonate

2. Iron Carbonate

3. Zinc Carbonate

4. Magnesium Carbonate

Summary - The metal which decomposes the fastest will give off the most

CO2. The metal which decomposes the slowest will give off the

least CO2.

Analysis

The order of how the metal decomposed are shown below. The fastest is shown first:

. Iron Carbonate

2. Copper Carbonate

3. Zinc Carbonate

4. Manganese Carbonate

5. Magnesium Carbonate

My first prediction that Magnesium would be the hardest to thermally decompose was correct. Magnesium was the hardest to thermally decompose, because as this metal is near to the top of the reactivity series it has a strong hold on its carbonates. The investigation shows that reactive metals give off little carbon dioxide when their carbonate is heated. This is because some of the bonds that magnesium has with its carbonates aren't broken meaning that no carbon dioxide is given off. Only a few of the bonds are broken, therefore only a small amount of carbon dioxide is given off.

On the graph the line which represents magnesium doesn't have a steep curve. This is because only a small amount of carbon dioxide is given off.

The small amount of carbon dioxide given off shows that the atoms of magnesium are stable.

In comparison to the above my prediction of the metal that would thermally decompose the fastest was incorrect. I predicted that Copper would decompose the fastest, releasing the most carbon dioxide. I predicted this because Copper was the lowest metal in the reactivity series that I used. However, the metal carbonate, that thermally decomposed the quickest releasing the most carbon dioxide was Iron Carbonate. Copper was however very close behind Iron. I didn't expect Iron the thermally decompose the fastest because there are quite a number of metals between Iron and copper.

I predicted that Copper would be the easiest metal to thermally decompose because as it is low down in the reactivity series it doesn't have a strong hold on its carbonates. Therefore as soon as Iron is heated the bond it has with its carbonates are broken and are released as carbon dioxide. Most of the bonds are broken, because Iron doesn't have a strong hold on its carbonate, meaning that a large volume of carbon dioxide is released as the iron carbonate is heated. Also I wouldn't have predicted that Iron would react in this way, because as it is in the middle of the reactivity series the atoms would be fairly stable. The graph also supports what has happened. The curve on the line for Iron Carbonate is very steep displaying that a large volume of carbon dioxide was given off when the Carbonate. The curve on the line for copper carbonate is not as steep as the curve for Iron Carbonate. This shows that Iron gave off a lot of carbon dioxide, a lot more than copper.

Having now done I can predict where Manganese would lie in the reactivity series. Manganese is about as reactive as Magnesium. I think that Manganese lies just below Magnesium in the reactivity series, and above Aluminium.

Evaluation

I think that the Iron Carbonate being the metal which thermally decomposed the fastest was an anomalous result. I think this because Iron was too high in the reactivity series to react this way. The volume of Carbon Dioxide that was given off shouldn't have been as high. This could be an anomalous result because the Iron Carbonate was contaminated with a metal lower down in the reactivity series.

If there had been more time allocated for this experiment it would have been better for each group to test all of the carbonates. Instead of each group doing one carbonate and then find out the results for the other carbonates from other members in the class. Therefore if any anomalous results occurred you could use another groups results. Also more repetitions should have been done to stop any anomalous results

When measuring the weight of the carbonates it would have been better not to use the same mass for each carbonate. Instead the same number of molecules should have been used for each carbonate. If one carbonate had less molecules than another carbonate, it thermally decomposes quicker, than the carbonate with more molecules.

If I could have used a bigger trough I would have because the one that was used was too small. It was hard to get your hand under the cylinder and put the tube under the cylinder.

The time intervals should have been more varied. It was hard to keep reading the level of water after every ten seconds because was hard to judge where the water level was and every ten seconds was too frequent.

Overall I don't think my results were as accurate as they could have been because not enough repetitions were done. Also you don't now how reliable other peoples results are.

If I had time to do the graph again I would have drawn it landscape instead of portrait. The reason for this is that the graph was too squashed together, meaning it was difficult to plot the results and draw a line of best fit without getting the points mixed up.

If I could do this investigation again I would:

? Do more repetitions

? Test each carbonate myself

? Use the same amount molecules in each carbonate, instead of the same mass carbonate.

? Use a bigger trough

? Have larger time intervals for measuring the amount of Carbon Dioxide.