Question

(i)What mass of carbon dioxide (in kg) is produced upon the complete combustion of

18.9 L of propane (approximate contents of one 5-gallon tank)? Assume that the


density of the liquid propane in the tank is 0.621 g/mL . (Hint: Begin by writing

a balanced equation for the combustion reaction.)

m=? kg



(ii) A 22.0 - mL sample of an unknown H3PO4 solution is titrated with a 0.110 M NaOH

solution. The equivalence point is reached when 18.60 mL of NaOH solution is added.


What is the concentration of the unknown H3PO4 solution? The neutralization reaction is as

follows:

H3PO4(aq) + 3NaOH(aq) ---> 3H2O(l) + Na3PO4(aq)


M=?

Answer 1

Answer:

The answer to your question is:

a) 35211 g of CO2

b) Molarity = 0.03

Explanation:

a)

mass of CO2 = ?

Volume = 18.9 L

density = 0.621 g/ml

Reaction

                C₃H₈    +    5O₂      ⇒     3CO₂     +     4H₂O

Density = mass / volume

mass = density x volume

mass = 0.621 x 18900

mass = 11737 g

MW of C3H8 = 44 g

MW of 3CO2 = 132 g

                         44 g of C3H8  -------------------  132 g of CO2

                     11737 g of C3H8 --------------------   x

                        x = (11737 x 132) / 44

                       x = 35211 g of CO2

b)             H3PO4(aq) + 3NaOH(aq) ---> 3H2O(l) + Na3PO4(aq)

                 22 ml             18.6 ml

                  [?]                  0.11 M

Calculate moles of NaOH

n = M x V

n = 0.11 x 0.0186

n = 0.0020 moles

From the balance reaction

               1 mol of H3PO4 ------------------  3 moles of NaOH

                x                        ------------------   0.0020 moles

               x = (0.002 x 1) / 3

              x = 0.0007  mol of H3PO4

Molarity = 0.0007 / 0.022

Molarity = 0.03