Question

In a chemical reaction, a student react 1.315 grams of elemental Mg solid in the lab (with unlimited amount of oxygen) and produced MgO.

2Mg(s) + O2(g) 2MgO(s)

(A) Determine the number of moles of Mg solid used in this reaction?

(B) If all the magnesium reacted to form the magnesium oxide, how many moles of magnesium oxide was produced?

(C) What mass of magnesium oxide was produced?

(D)Name the general type of reaction shown above?

Answer 1

A) moles = mass / molar mass  

moles = 1.315 / 24.3

moles = 0.054

moles of Mg used = 0.054

B) according to balanced reaction

2 moles Mg gives 2 moles MgO

0.054 moles Mg gives 0.054 x 2 / 2 = 0.054 moles MgO

moles of MgO formed = 0.054

C) mass of MgO = moles x molar mass

mass of MgO = 0.054 x 40.3

mass of MgO = 2.18 g

D) given reaction is example of combination reaction.