Aim: to perform a firsthand investigation to compare the physical and chemical properties of magnesium and oxygen when they are experimented to form magnesium oxide Theory: The empirical formula of a compound is the formula that tells us the ratio in which the atoms are present in the compound. To calculate an empirical formula: -
Write down the masses of all of the elements present
Convert masses to moles (by dividing by atomic weights in grams) -
Divide through by the smallest number of moles to get a simple ratio -
Of the numbers are not close to whole numbers, multiply through a suitable factor so that they become close to a whole number -
Round off the numbers to get whole numbers and use these to write the empirical formula. Method:
What is a risk?
How is it a risk?
How to reduce the risk?
the process involving lifting the crucible lid during heat application
This can be a risk as using hands to pick up the lift can cause burns to the hand
The use of tongs to hold the lid as it is being lifted will avoid the risk The mixing of universal indicator with the magnesium oxide
The test tube may slip out of the hand when shaking and shatter onto the ground where other students are working
This can danger of this risk can be reduced if the mixing process is completed in the sink. The use of a Bunsen burner
The Bunsen burner is on fire so it can cause personal injury to oneself.
Giving extra caution around the experiment and the use of personal protection such as glasses and apron.
Set up the experiment as shown above in the diagram
Heat the magnesium strip using the Bunsen burner
Lift the lid of the crucible every 5 minutes
After heating the strip wait for the crucible to cool
Pour the reminiscent magnesium into a test tube
Fill half of the test tube with water
Add universal indicator
Shake the test tube until the colour of the substance has turned purple/blue Results:
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