RESEARCH QUESTION: DOES DIFFERENT TYPE OF ORGANIC FERTILIZERS CONTAIN DIFFERENT PERCENTAGE OF AMMONIUM SULPHATE WHICH IS A SOURCE OF NITROGEN?
Plants need a supply of nitrogen for growth. Atmospheric nitrogen is ‘fixed’ by bacteria and it is then absorbed through the roots in the form of nitrogen compounds. Dense plantings , such as in lawns, use up the available nitrogen at a faster rate than it can be fixed from the atmosphere. Additional nitrogen must be added in the form of fertiliser such as ammonium sulfate.
Ammonium sulphate is widely used as fertilizer. Ammonium sulphate is the source of both nitrogen and sulphur that is essential to plants. Nitrogen is so vital because it is a major component of chlorophyll, the compound by which plants use sunlight energy to produce sugars from water and carbon dioxide. It is also a major component of amino acids, the building blocks of proteins. Without proteins, plants wither and die.
In this experiment, I will be investigating the percentage of ammonium sulphate in different types of organic fertilizer by boiling the fertilizer in a Sodium hydroxide solution and titrate it with hydrochloric acid to determine the amount of ammonium sulphate contained in the fertilizer.
Methods of controlling
Type of organic fertilizer
Percentage of Ammonium Sulphate
Size and uncertainty
Animal Manure fertilizer
0.1 mol dm-3 of HCl and 1.0 mol dm-3 NaOH are prepared.
Weigh 1 gram of fertilizer accurately using an electronic balance.
Put the fertilizer inside a 250 ml conical flask.
Add 25 ml of 1.0 mol dm-3 NaOH and 50 ml water to the sample.
Put a small funnel in the top and boil the solution gently for 15 – 20 minutes, topping up with water if required.
Wash the funnel into the flask and then transfer the contents into a 250 ml volumetric flask and make up to the mark.
Using 25 ml phenolphthalein indicator, titrate with 0.1 mol cm-3 HCl.