Many of our daily activities result, directly or indirectly, in the emission of

Question

Many of our daily activities result, directly or indirectly, in the emission of CO_2 into the environment. We burn gasoline in our cars, we combust propane in our stoves, and natural gas in our heating systems. We use electricity that is largely generated by burning coal in power plants and we live in houses and cities built with cement produced in a process in which CO_2 is also formed. The table shown to the right includes data for the average consumption of oil, coal, and natural gas per person per year in the US. Although oil, coal, and natural gas are mixtures of many different substances, to simplify the calculations assume that oil is mostly made of heptanes (C_7H_16),natural gas is made of methane (CH_4), and that the mass percentage of carbon in the coal we use is close to 90%. Thus, the following chemical equations represent the production of CO_2(g) from these sources: C_7H_16(l) + O_2(g) rightarrow CO_2(g) + H_2O(g) CH_4(g) +O_2(g) rightarrow CO_2(g) + H_2O(g) C(s) + O_2(g) CO_2(g) Use the information provided to calculate the TOTAL mass of CO_2 produced per person per year in the US. Express your results in tonnes of CO_2.

Explanation / Answer

To calculate: CO2 produced per person per year

Let us solve the problem fuel by fuel

1) OIL:

It is used = 3.5m^3 / person / year = 3.5 X 10^3 L / person / year

combustion equation is

C7H16(l) + 11O2 --> 7CO2(g) + 8H2O

Density of oil = 0.8 Kg / L

So mass of oil used per person per year = Volume X density = 3.5 X 10^3 L X 0.8 Kg / L = 2.8 Kg = 2800 grams

Now as per stoichiometry of comubstion equation of heptane , one mole (100g) will give 7 moles of CO2

So 2800 grams will give = 7 X 2800 / 100 moles of CO2 = 196 moles of CO2

Molecular weight of CO2 = 44g / mole

So mass of CO2 produced = 196 X 44 = 8624 grams = 8.624 Kg per person per year

2) GAS

The comubstion reaction is

CH4 + 2O2 --> CO2(g) + 2H2O(g)

As per stoichiometry , 1mole of CH4 will give one mole of CO2

Or 22.4 L will give 22.4 L of CO2 gas

Gas used = 2125 m^3

So 2125m^3 of gas will give 2125 m^3 CO2 Or 2125 X 10^3 L of CO2

As per give infromation 22.4 L of gas equals 1 mole of CO2

so 1L = 1 /22.4 moles of CO2

So 2125 X 10^3 L will be = 2125 X 10^3 / 22.4 moles = 94866.07 moles

The mass of 1 mole of CO2 = 44grams

so mass of 94866.07 moles = 44 X 94866.07 grams = 4174107.08 grams = 417.4107 Kg per person per year

3) COAL

we know that 1 tonne = 1000 Kg

so 3.2 tonne = 3200 Kg

Out of this carbon % = 90%

So mass of carbon = 0.9 X 3200 = 2880 Kg

C(s) + O2 --> CO2(g)

as per stoichiometry 1 mole of Carbon will give 1 mole of CO2 or 44 grams of CO2

12 gram will give 44 g of CO2

1 gram will give 44/12 g of CO2

2880 Kg will give = 44 X 2880 / 12 Kg = 10560 Kg of CO2 per person per year

Total CO2 produced = 10560 + 417.41 + 8.624 = 10986.034 Kg per person per year = 10.986034 tonnes per person per year

Related Questions

Navigate

• Browse (All)
• Browse M
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.