Which carbonates decompose

All the nitrates in this Group undergo thermal decomposition to give the metal oxide, nitrogen dioxide and oxygen. The nitrates are white solids, and the oxides produced are also white solids. Brown nitrogen dioxide gas is given off together with oxygen.

Magnesium and calcium nitrates normally have water of crystallisation, and the solid may dissolve in its own water of crystallisation to make a colourless solution before it starts to decompose. As you go down the Group, the nitrates also have to be heated more strongly before they will decompose.

Both carbonates and nitrates become more thermally stable as you go down the Group. The ones lower down have to be heated more strongly than those at the top before they will decompose. This page offers two different ways of looking at the problem. You need to find out which of these your examiners are likely to expect from you so that you don't get involved in more difficult things than you actually need.

You should look at your syllabus, and past exam papers - together with their mark schemes. Note: If you are working towards a UK-based exam A level or its equivalent and haven't got copies of your syllabus and past papers follow this link to find out how to get hold of them. Detailed explanations are given for the carbonates because the diagrams are easier to draw, and their equations are also easier.

Exactly the same arguments apply to the nitrates. It has a high charge density and will have a marked distorting effect on any negative ions which happen to be near it. Its charge density will be lower, and it will cause less distortion to nearby negative ions. If you worked out the structure of a carbonate ion using "dots-and-crosses" or some similar method, you would probably come up with:.

This shows two single carbon-oxygen bonds and one double one, with two of the oxygens each carrying a negative charge. Unfortunately, in real carbonate ions all the bonds are identical, and the charges are spread out over the whole ion - although concentrated on the oxygen atoms. We say that the charges are delocalised. This is a rather more complicated version of the bonding you might have come across in benzene or in ions like ethanoate.

For the purposes of this topic, you don't need to understand how this bonding has come about. Note: If you are interested, you could follow these links to benzene or to organic acids. Either of these links is likely to involve you in a fairly time-consuming detour! The next diagram shows the delocalised electrons. The shading is intended to show that there is a greater chance of finding them around the oxygen atoms than near the carbon.

Now imagine what happens when this ion is placed next to a positive ion. It takes a lot of energy to decompose the carbonates of metals that are high in the reactivity series such as sodium and magnesium.

In fact, most of the Group 1 metal carbonates do not decompose at the temperatures reached by a Bunsen burner. What do carbonates produce when decomposed? Chemistry Chemical Reactions Decomposition Reactions. Ernest Z. When metal carbonates are heated, they break down to form the metal oxide and carbon dioxide gas.

Here are some examples. The difficulty of this decomposition reaction depends on the reactivity of the metal in the metal carbonate. Many metal carbonates can take part in thermal decomposition reactions. Which metal hydroxide does not decompose when heated? How do nitrates decompose? What happen when sodium carbonate is heated? What happens when lithium nitrate is heated? Which is least thermally stable? What is the Colour of calcium carbonate?

What is the Colour of sodium carbonate? Is sodium carbonate thermally stable? Why is caco3 more stable than mgco3? How does sodium carbonate decompose? What happens when calcium nitrate is heated? What happens when magnesium nitrate is heated? Which metal oxides is easiest to decompose on heating?

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