Magnesium can be used as a “getter” in evacuated enclosures to react with the last traces of oxygen. (the magnesium is usually heated by passing an electric current through a wire or ribbon of the metal) If an enclosures of 0.452L has a partial pressure of O2 of 3.5 x 10^-6 torr at 27 Celsius, what mass of magnesium will react according to the following equation?

2 Mg (s) + O2 (g) —> 2 MgO (s)

Answer is 4.1 x 10^-9 g Mg

3 answers

find moles of O2 ... p v = n r t

two moles of Mg for each mole of O2

calculate mass of Mg
Moles of O2 is 0.0625023

What’s my next step after?
now you need twice 0.0625023 moles of Mg. How much mass is that.