Use the equation below to answer the following two questions.
2C2H6 + 7O2 ---> 4CO2 + 6H2O
8. How many moles H2O are produced when 94.5 moles C2H6 decomposes completely?
a. 185.3 moles
b. 267.5 moles
c. 31.5 moles
d. 283.5 moles

9. How many grams C2H6 are needed to completely react with 42 grams O2?
a. 11.1 grams
b. 137.55 grams
c. 0.37 grams
d. 142.08 grams

answer is: c. the experiment shows that the red substance experienced a chemical change.

this is chemical change (chemical reaction), because two new substances are formed (metalig liquid and gas), the atoms are rearranged and the reaction is followed by an energy change.

this is example of chemical decomposition.

chemical decomposition (analysis) is the separation of a single chemical compound into its two or more elemental parts or to simpler compounds.  

chemical decomposition is opposite of chemical synthesis.

answer : (a) volume of the gas = 8.67 ×   l

                (b) second virial coefficient b = -1.21226 l/mole

solution :   given,     t = 300k

                                p = 20atm

                                z = 0.86

                                n = 8.2 mmoles = 8.2 × moles

                                r =   0.082 l atm/k/mol

        find,     (a) volume of gas   and (b) second virial coefficient b at 300k.

formula used :            

                          and            

(a)            

                    = \times 0.082\times 300}{20}[/tex]

                    = 8.67 ×   l

(b)      

                    = (0.00867-1) × 8.659

                    = - 8.5839 l/mole