97.22 grams of magnesium is needed.
Step-by-step explanation:
The molar ratio of Mg to O2 to make MgO is 2:1
Here, we have 2 moles of O2, therefore we need 4 moles of Mg.
1 mol of Mg = 24.305 g
Therefore
4 moles of Mg = 4
24.305 g
= 97.22 g
Hence we need 97.22grams of magnesium are needed to completely reactwith 2.00 mol of O2 in the synthesis reaction that producesmagnesium oxide.