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ISA Assessment Monday, 21 March 2011
Why Are Chemical Calculations So Important?
Chemical calculations are vitally important in today's industries. They are often used in
pharmaceutical companies and research centres for the development of new drugs and food
preservatives and additives. Chemical calculations such as the Mole help a scientist write the
quantity of a substance in an "algebraic" form and prevent the scientist wasting time on writing big,
long numbers. A chemical calculation such as the atom economy of an experiment helps scientist
notice whether it is economical to do the experiment or if it is wasting too much in the reaction.
Basically, chemical calculations play a big role in today's companies and provide accuracy to a minute
In our class we conducted an experiment to see how much magnesium ribbon got oxidised, and
how much turned into a wasted product such as carbon monoxide if it was incomplete combustion.
First we got a heatproof mat and a Bunsen burner and set them safely
In place. We then got a tripod and set it above the Bunsen burner.
Next we got a ribbon of magnesium (Mg) and put it in a crucible. Using a
Splint we lit the Bunsen burner and placed it under the crucible. We
heated it until we were sure the crucible was very hot, but not hot
enough to make the magnesium react. We quickly opened the crucible
to let in some oxygen and the closed the lid again, we did this by using
tongs because the crucible was quite hot.
Mass 1- Crucible + Lid: 30.7g
Mass 2- Crucible + Lid + Magnesium Ribbon: 30.74g
Mass 3- Crucible + Lid + Product: 30.72g
Change in magnesium' weight: 0.02g
Mass of magnesium: 0.02g
Mass of oxygen: 0.02g
"Find the mass of magnesium and oxygen in the product, assuming no loss of material?"
The equation of the reaction is: 2Mg +O2= 2MgO
No. of moles = Mass / R.A.M
Mass = No. of moles x R.A.M
It takes 2 moles of magnesium and 2 moles of oxygen in order to form 2 moles of magnesium
Magnesium: 2 x 24 = 48 g
Oxygen = 2 x 16 = 32
48 +32 = 80 / 2 = 40