Question

When 1g mg is burnt with 1g O2, limiting reagent is ______
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Answer 1

Balanced reaction is:

2Mg+O

2

→2MgO

According to the reaction 2 mol (or 2×24.3=48.6g) Mg reacts with 32 g oxygen. 1 g of Mg requires =

48.6

32

=0.66g oxygen but given oxygen is 0.5 g ∴ oxygen is the limiting reagent

0.5 g oxygen can burn ==

32

48.6 ×0.5=0.75g Mg

Excess of Mg left =1−0.75=0.25g