Question

a. Pentane (200 g) is combusted to produce CO2. Derive and balance the chemical equation for this reaction. List the oxidation state of all species. (3 points)

b. All of the CO2 produced in the combustion is taken up by plants during photosynthesis to produce glucose and oxygen. Derive the balanced equation. (3 points)

c. How many grams of glucose are produced from the 200 g of pentane combusted? (3 points)

Answer 1

a)

balanced equation :

C5H12 + 8 O2 ----------------------------> 5CO2   + 6H2O

oxidation states of all elements :

C5H12 + 8 O2 ----------------------------> 5CO2   + 6H2O

in the reactants side:

C-------------> -2.4

H ---------------> +1

O----------------> 0

in the products side:

C ----------------> +4

O --------------> -2

H---------------> +1

b)

balanced equation

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

c)

C5H12 + 8 O2 ----------------------------> 5CO2   + 6H2O

72g                                                 220g

200 g                                                ?

mass of CO2 = 611 g

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

264g                                               180g

611 g                                                ?

glucose produced = 180 x 611 / 264

                          = 417 g

mass of glucose produced = 417g