When heated in a crucible, magnesium metal reacts with oxygen from the air to form magnesium oxide in a synthesis reaction. How do you expect the mass ofthe crucible and its contents to change after the reaction?

1 Answer
Jun 8, 2017

Answer:

The mass of the crucible is constant. The mass CONTAINED by the crucible will increase..........

Explanation:

We can represent the oxidation so..........

#Mg(s) +1/2O_2(g) stackrel(Delta)rarrMgO(s)#

And thus combustion of one equiv magnesium metal, #24.3*g#, should lead to formation of approx. #40*g# magnesium oxide. And thus the mass contained by the crucible should almost double.

Often when you do the experiment, you lose some of mass, i.e. the #MgO# ash is lost from the crucible. Be careful and don't burn yourself on the crucible.