Question

2 Mg (s) + O2 (g)  2 MgO (s)

1. If the magnesium is burned uncontrolled, it burns brightly and escapes as smoke, how will this error affect the reported mass of the

a. magnesium in the sample?

b. oxygen in the sample?

c. magnesium oxide?

(It may be helpful to assume an initial mass of Mg then calculate the effect of the change on your final results.)

Answer 1

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

The magnesium is burned uncontrolled.

(a). The magnesium is burned uncontrolled, it burns brightly and escapes as smoke, This will reduce the mass of magnesium in the sample. As, magnesium burns and evaporates in the air leaving behind less amount of magnesium.

(b). As, 1 mol of Mg reacts with 1 mol of O atoms to form 1 mol of MgO.

when it burns some of the magnesium evaporates, thus the amount of oxygen will increase in the sample.

(c). Burning Mg in air leads both to MgO and Mg₃N₂. Some of the magnesium involves in the formation of Mg₃N₂ so the amount of MgO obtained is reduced as is was expected. The amount of MgO is reduced.