Using the mole to work out the empirical formula magnesium oxide.
Magnesium reacts with oxygen to form magnesium oxide. We can find the ratio of magnesium atoms to oxygen atoms present in a sample of magnesium oxide.

Step 1 Weigh the empty crucible.


Record the weight - 32.34 grams

 

Step 2 Clean a strip of magnesium ribbon (approximately 0.5 grams) with steel wool. This scrapes off the magnesium oxide already formed. Place the magnesium ribbon in the crucible.

Step 3 Weigh the crucible with the magnesium ribbon.
32.74 grams

 

Step 4 Heat the crucible over a Bunsen flame. Periodically lift the lid to allow oxygen to enter.

Do not leave the lid open too long as magnesium oxide will escape.

Step 5 When significant reaction is noticed, by the formation of a grey powdery substance, remove the flame and allow the crucible to cool. Weigh the crucible and record its mass. Place the crucible under the flame and repeat step 4. Keep on weighing the crucible until no mass increase is noticed.

 

Step 6 Weigh the crucible for the last time
33.30 grams

Calculate the empirical formula for magnesium oxide according to the results above.

Continue with the calculations

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