Question

Using the equation:      2 NO     +     O2       à    2 NO₂

Determine the limiting reactant if given 1.0 mol NO and 1.0 mol O₂

Determine the limiting reactant if given 4.2 mol NO and 2.0 mol O₂

Determine the limiting reactant if given 10.0 grams NO and 10.0 grams O₂

Identify the species that is oxidized and the species that is reduced in each of the reactions below:

Fe     +     Cu²⁺     à Fe²⁺     +      Cu

Mg     +    Fe²⁺     à    Mg²⁺     +    Fe

Answer 1

1)

a)

Balanced chemical equation is:

2 N2 + O2 ---> 2 NO2

2 mol of N2 reacts with 1 mol of O2

for 1 mol of N2, 0.5 mol of O2 is required

But we have 1 mol of O2

so, N2 is limiting reagent

b)

2 mol of N2 reacts with 1 mol of O2

for 4.2 mol of N2, 2.1 mol of O2 is required

But we have 2 mol of O2

so, O2 is limiting reagent

c)

Molar mass of N2 = 28.02 g/mol

mass(N2)= 10.0 g

use:

number of mol of N2,

n = mass of N2/molar mass of N2

=(10 g)/(28.02 g/mol)

= 0.3569 mol

Molar mass of O2 = 32 g/mol

mass(O2)= 10.0 g

use:

number of mol of O2,

n = mass of O2/molar mass of O2

=(10 g)/(32 g/mol)

= 0.3125 mol

Balanced chemical equation is:

2 N2 + O2 ---> 2 NO2

2 mol of N2 reacts with 1 mol of O2

for 0.3569 mol of N2, 0.1784 mol of O2 is required

But we have 0.3125 mol of O2

so, N2 is limiting reagent

2)

a)

Oxidation state of Cu changes from +2 to 0

So, Cu2+ is getting reduced

Oxidation state of Fe changes from 0 to +2

So, Fe is getting oxidised

b)

Oxidation state of Fe changes from +2 to 0

So, Fe2+ is getting reduced

Oxidation state of Mg changes from 0 to +2

So, Mg is getting oxidised