Question

2H₂O₂ ---> 2H₂O + O₂

Show all work.

a. Given 20.0 grams of H₂O₂, how many grams of water will the reaction yeild?

b. How many grams of hydrogen peroxide would you need to get 20.0 grams of water?

c. How many grams of hydrogen peroxide would you need to get 20.0 grams of O₂?

Answer 1

a)

Molar mass of H2O2 = 2*MM(H) + 2*MM(O)

= 2*1.008 + 2*16.0

= 34.016 g/mol

mass of H2O2 = 20 g

mol of H2O2 = (mass)/(molar mass)

= 20/34.016

= 0.588 mol

From balanced chemical reaction, we see that

when 2 mol of H2O2 reacts, 2 mol of H2O is formed

mol of H2O formed = moles of H2O2

= 0.588 mol

Molar mass of H2O = 2*MM(H) + 1*MM(O)

= 2*1.008 + 1*16.0

= 18.016 g/mol

mass of H2O = number of mol * molar mass

= 0.588*18.016

= 10.6 g

Answer: 10.6 g

b)

Molar mass of H2O = 2*MM(H) + 1*MM(O)

= 2*1.008 + 1*16.0

= 18.016 g/mol

mass of H2O = 20 g

mol of H2O = (mass)/(molar mass)

= 20/18.016

= 1.1101 mol

From balanced chemical reaction, we see that

when 2 mol of H2O reacts, 2 mol of H2O2 is formed

mol of H2O2 formed = moles of H2O

= 1.1101 mol

Molar mass of H2O2 = 2*MM(H) + 2*MM(O)

= 2*1.008 + 2*16.0

= 34.016 g/mol

mass of H2O2 = number of mol * molar mass

= 1.1101*34.016

= 37.8 g

Answer: 37.8 g

c)

Molar mass of O2 = 32 g/mol

mass of O2 = 20 g

mol of O2 = (mass)/(molar mass)

= 20/32

= 0.625 mol

From balanced chemical reaction, we see that

when 1 mol of O2 reacts, 2 mol of H2O2 is formed

mol of H2O2 formed = (2/1)* moles of O2

= (2/1)*0.625

= 1.25 mol

Molar mass of H2O2 = 2*MM(H) + 2*MM(O)

= 2*1.008 + 2*16.0

= 34.016 g/mol

mass of H2O2 = number of mol * molar mass

= 1.25*34.016

= 42.5 g

Answer: 42.5 g