Question

Pure magnesium metal is often found as ribbons and can easily burn in the presence of oxygen. when 4.81 g of magnesium ribbon burns with 7.46 g of oxygen, a bright, white light and a white, powdery product are formed

Answer 1

Metals in their pure form are highly flammable. In this item, we are given with the pure magnesium metal in ribbon form reacting with oxygen in the combustion process. The equation that would best illustrate this given is,
   
                 2Mg + O₂ --> 2MgO

In this item, we are to determine the amount of MgO that can will be formed. 

 Magnesium
         (4.81 g)(1 mol Mg/24.31 g Mg)(2 mol MgO/2 mol Mg)(40.3 g MgO/1 mol MgO)
              = 7.97 g MgO

Oxygen
        (7.46 g)(1 mol O2/32 g O2)(2 mol MgO/1 mol O2)(40.3 g MgO/1 mol MgO)
              = 18.79 g MgO

This means that the amount of MgO produced is 7.97 g.