These metal carbonates are found in the nature, calcium carbonate occurs as chalk, limestone and marble, chalk was formed; often in deposits of hundred meters thick form the exoskeletons of small marine organisms. The thermal stability of the group 2 carbonates increases form magnesium carbonate to barium carbonate. Group 1 metal carbonates are soluble when water is added this is a colourless solution and one of the differences when relating to group 1 and group 2 carbonates. All carbonates react with acid to produce carbon dioxide this is shown by this equation: Co3--+H+ Co2+H2o. The carbonates of sodium and potassium, Na2Co3 and K2Co3, only decompose very slowly at very high temperatures they are thermally stable and they are freely soluble in water. Therefore the group 1 carbonates were soluble and the group 2 carbonates were insoluble when water was added.
Now I will examine my second experiment which was about the nitrates, there where three tests which were carried out involving potassium nitrate, lead nitrate and strontium nitrate. Nearly all metal nitrates decompose when heated to give the metal oxide plus the gases nitrogen dioxide and oxygen. Potassium nitrate behave very differently it decompose to give the nitrate and oxygen. Group 1 nitrates are thermally stable whereas group 2 nitrates are thermally stable only when you have a high temperature. When the potassium nitrate was heated we saw that it became a liquid with no colour and then turned into a gelatinous solid.
When strontium nitrate was heated it made popping sounds and became a liquid which started to become yellow into green and then brown, some light fumes were given off and there was gas at the top of the test-tube. Group 1 and 2 nitrates are all soluble, all the nitrates are soluble this is the chemical formula Sr(No3)2 Δ BaO+No3. Lead nitrate is used in this test as a reference because this is the normal behaviour of a metal nitrate on heating. Lead nitrate was popping going into yellow fumes which went orange to brown and nitrogen oxide was given off this is shown by this equation: Pb(No3)4 Δ PbO+4No2+3/2O2.
Lithium nitrate is one if the peculiar nitrates this behaves like magnesium nitrate and like the elements in its group. This is one piece of evidence for the diagonal relation ship between lithium and magnesium nitrate. Diagonal relationship is the tendency of the element in the first row to behave like the element in the second row.
Now I will talk about my third experiment which was about the reaction of metallic elements with water. The experiment was carried out using potassium and sodium. When the sodium was first put into the water it fizzed around for a while in a spherical shape giving of gas due to the fizz this is because all group 1 metals react with water to give off hydrogen gas and the hydroxide of the metal. The reaction of the group 1 metals as you go down the group increases when put in water. When the potassium was added to the water it caught fire and did the same as sodium except it was on fire and towards the end it exploded giving of a steamy gas which of course is hydrogen. When red litmus paper was added to the potassium reaction it went blue this is because all group 1 metals react with water to leave an alkaline solution of the hydroxide, these metals are stored in a oil which stops it from reacting with the oxygen. Group 2 metals react in a similar way but more slowly, the reactions get more vigorous as one proceeds down the group, magnesium only reacts with the water when it is boiled. The chemical formula for all group 1 metals reacting with water is 2M+2H2O 2MOH+H2 and the chemical formula of all group 2 metals reacting with water is M+2HOH M++(OH)-2+H2.
On my fourth experiment I conducted the following experiment where it included elements from group 1 which were sodium, potassium and the group 2 elements are barium, strontium and calcium. Each of these elements were tested with other common anions which are chlorine, sulphur, carbonate, nitric acid and hydroxide we used 1M of these anions and group 1 and 2 salts. When the group 1 elements were mixed with chlorine they were a colourless solution so were the group 2 elements. When I added nitric acid to the group 1 salts they were colourless because all group 1 nitrates are soluble so are group 2 nitrates and the equation for the chlorides and nitrates are mentioned in this essay. When I added sulphuric acid to the common salts group 1 salt didn’t react the stayed a colourless solution but when the group 2 salts were added to the dilute acid they formed a whit precipitate form where the formula equation is Ba2+(aq)+So42-(aq) BaSo4(s) also the solubility decreases as you go down group 2. The only strange thing we saw was that when calcium was added we saw no visible reaction meaning that it remained colourless solution. Barium sulphate is used in x rays because barium is a heavy element and x rays can’t penetrate it.
When hydroxide anions were added to the common salts of group 1 we saw no change it remained colourless this is because group 1 hydroxides are soluble in water and all hydroxides are white. When group 2 salts were added to the hydroxide all of them produced the same result which was a cloudy precipitate form also the solubility varies as you go down the group and group 2 oxides react with water to produce hydroxide. Here is the formula equation for barium hydroxide Ba(OH)2(s)+Aq Ba2+(aq)+2OH-(aq) also indigestion tablets contain Mg(OH) to neutralise excess acid in the stomach.
When carbonate was added to the common salts of group 1 it still remained a colourless solution because all group 1 carbonates as I’ve stated are soluble and the formula equation is stated in this essay. When group 2 salts were added to carbonate we saw that all the group 2 salts were a white precipitate form and all group 2 salts are insoluble.
On my fifth experiment I did a flame test using nichrome wire and the solid of group 1 and 2 compounds. The solids included sodium, potassium, calcium, strontium and barium. The colour of sodium is orange the colour of potassium is lilac the colour of calcium is brick red the colour of strontium is crimson red and the colour of barium is green. The characteristic flame colours arise from transitions within the atom. Heat energy from the flame excites and electron to a higher energy level. The electron returns to a lower level and the excess energy is released as light energy. The frequency of the flame colour depends upon the difference between the energy levels involved.