Question

15) A substance used in manufacturing gasoline consists of finely divided platinum supported on an inert solid. Suppose that the platinum is formed by the high temperature reaction between platinum (IV) oxide and hydrogen gas. The other product is water.
a) Write and balance the equation

b) How many grams of hydrogen are needed to produce 1.0 g of platinum metal?

c) How many moles of water are produced at the same time? How many grams?

(Please show work, thanks.)

Answer 1

Answer:

a) PtO₂ + 2H₂ ⟶ Pt  +  2H₂O

b) 0.021 g

c) 0.010 mol; 0.18 g

Step-by-step explanation:

a) Balanced equation

We know we will need a balanced equation with masses and molar masses, so let’s gather all the information in one place.  

M_r:                2.016  195.08  18.02

            PtO₂ + 2H₂ ⟶ Pt  +  2H₂O

m/g:                              1.0

b) Mass of H₂

(i) Calculate the moles of Pt

n = 1.0 g Pt  × (1 mol Pt /195.08 g Pt)

  = 5.13 × 10⁻³ mol Pt

(ii) Calculate the moles of H₂

The molar ratio is (2 mol H₂/1 mol Pt)

n = 5.13 × 10⁻³ mol Pt × (2 mol H₂/1 mol Pt)

  = 0.0103 mol H₂

(iii) Calculate the mass of H₂

m = 0.0103 mol H₂× (2.016 g H₂/1 mol H₂)

m = 0.021 g H₂

You need 0.021 g H₂ to produce 1.00 g Pt.

c) Moles of water

The molar ratio is (2 mol H₂O/1 mol Pt)

 Moles of H₂O = 5.13 × 10⁻³ mol Pt × (2 mol H₂O/1 mol Pt)

                        = 0.010 mol H₂O

Mass of water = 0.010 mol H₂O × (18.02 g H₂O/1 mol H₂O)

                        = 0.18 g H₂O