Based on the results above, the copper (II)sulphate contain the highest percent of water
compare to sodium thiosulphate and the biscuits, whereas the biscuits contain the lowest
percent of water compare to copper(II)sulphate and sodium thiosulphate.
Before heating, copper (II) sulphate, blue crystalline solid, act as hydrate which contain water.
After heating, the copper (II) sulphate become light blue crystalline solid because the bond
between the water molecule and copper (II) sulphate is broken which caused the copper (II)
sulphate to change its colour. Next, the melting point of sodium thiosulphate is 48.3°C,
whereas the boiling point of sodium thiosulphate is 100°C. Although the sodium thiosulphate
is heated in the oven with 120°C, sodium thiosulphate remains in liquid form because the
vapour pressure is equal to the pressure exerted on the sodium thiosulphate solution by its
surroundings. After sodium thiosulphate is heated and cool down, the temperature decreases
and below the melting point, solid white crystalline sodium thiosulphate is formed when stirred
the sodium thiosulphate solution with glass rod. Moreover, after heating the biscuits, the
biscuits have an unpleasant oily smell and look more crispy.
Furthermore, the critical steps for this experiment are after heating, the crucible with sample
must cool to room temperature before weight to get an accurate readings. If the crucible with
sample is weight without cooling down after heated, it might damage the weighing balance
because of the heat and causes the reading become inaccurate. When using the weighing
balance to measure the weight, put the sample into the crucible carefully to prevent the
sample from spreading over the weighing balance and cause the reading become inaccurate.
Last but not least, the precaution steps need to carry out in the experiment are the chemical
substances such as copper (II) sulphate must be avoid contact with eyes and skin because it can
causes skin irritation and eyes irritation. The chemical substance cannot be swallowed because
it is harmful to our body. After the experiment, the apparatus need to clean and the chemical
substances must dispose properly after used. The sodium thiosulphate must be separated from
strong oxidants because it react violently with strong oxidants. Finally, the sodium
thiosulphate must be keep in a tightly closed container in a dry and cool place.
First and foremost, hydrate is a solid crystalline substances with a specific number of water
molecules (H2O) bound to its atom. If the compound contain extra water molecules attached
to their crystal structure, the extra water molecules can be removed by undergo the process
of heating. The water molecules in hydrate wasn’t chemically bond because it can be
removed simply by heating. Hydrate can be classified as inorganic hydrates and organic
hydrates. Hydrates is commonly used in skin care products.
Next, anhydrous compound is a substances without water, known as an anhydrate. The
anhydrate is formed when the water molecule is removed from the hydrate by heating at a
high temperature. The anhydrate is highly soluble in water and have similar colour to the
original hydrate. Anhydrate commonly used in drying agent. The most commonly used
anhydrate is silica gel, keeping the surrounding area dry and the growth of molds can be
Furthermore, water content determination is important in food industry because of the legal
and labelling requirements, the amount of water must be limited that present in certain types
of food. Moreover, the food quality can be determined by the water content, because the
texture, taste and others can be affected by the water content present in the food. The water
content in food will cause the growth of microorganisms because microorganism active in a
high moisture condition and low temperature. To prevent the growth of microorganisms in
food, the food will be dried below the moisture content. To have a highest production yield
and best quality of food, the amount of water content required when processing the food must
know clearly. Last but not least, the water content will affect the cost of the food in market
although water is a cheap ingredient and manufacturers try their best to incorporate the food
to prevent the exceeding of maximum legal requirements. Finally, producing best quality of
food, the water content is often analysed before, during and after the manufacturing process.