Question

Consider respiration, one of the most common chemical reactions on earth.

C6H12O6 + 6 O2 → 6 CO2 + 6 H2O + energy

What mass of carbon dioxide forms in the reaction of 25.00 grams of glucose with 40.00 grams of oxygen? How much of the excess reactant will be left after the limiting reactant is completely used up? (C = 12.01 amu, H = 1.01 amu, O = 16.00 amu)

Mass of carbon dioxide = Blank 1 grams CO2

Mass of excess reactant remaining = Blank 2 grams of excess reactant left unreacted

Answer 1

1)

Molar mass of C6H12O6 = 6*MM(C) + 12*MM(H) + 6*MM(O)

= 6*12.01 + 12*1.01 + 6*16.0

= 180.18 g/mol

mass of C6H12O6 = 25.0 g

we have below equation to be used:

number of mol of C6H12O6,

n = mass of C6H12O6/molar mass of C6H12O6

=(25.0 g)/(180.18 g/mol)

= 0.1388 mol

Molar mass of O2 = 32 g/mol

mass of O2 = 40.0 g

we have below equation to be used:

number of mol of O2,

n = mass of O2/molar mass of O2

=(40.0 g)/(32 g/mol)

= 1.25 mol

we have the Balanced chemical equation as:

C6H12O6 + 6 O2 ---> 6 CO2 + 6 H2O

1 mol of C6H12O6 reacts with 6 mol of O2

for 0.1388 mol of C6H12O6, 0.8326 mol of O2 is required

But we have 1.25 mol of O2

so, C6H12O6 is limiting reagent

we will use C6H12O6 in further calculation

Molar mass of CO2 = 1*MM(C) + 2*MM(O)

= 1*12.01 + 2*16.0

= 44.01 g/mol

From balanced chemical reaction, we see that

when 1 mol of C6H12O6 reacts, 6 mol of CO2 is formed

mol of CO2 formed = (6/1)* moles of C6H12O6

= (6/1)*0.1388

= 0.8326 mol

we have below equation to be used:

mass of CO2 = number of mol * molar mass

= 0.8326*44.01

= 36.64 g

Answer: 36.6 g

2)

From balanced chemical reaction, we see that

when 1 mol of C6H12O6 reacts, 6 mol of O2 reacts

mol of O2 reacted = (6/1)* moles of C6H12O6

= (6/1)*0.1388

= 0.8326 mol

mol of O2 remaining = mol initially present - mol reacted

mol of O2 remaining = 1.25 - 0.8326

mol of O2 remaining = 0.4174 mol

Molar mass of O2 = 32 g/mol

we have below equation to be used:

mass of O2,

m = number of mol * molar mass

= 0.4174 mol * 32 g/mol

= 13.36 g

Answer: 13.4 g