Unit 3 - Elements of Change- Combustion, Carbon, and Climate

combustion

the reaction that occurs when a fuel burns in oxygen.

products of complete combustion

Carbon dioxide and water.

Products of incomplete combustion

Carbon monoxide, carbon, and water.

Why is complete combustion preferred over incomplete combustion?

Less harmful products like carbon dioxide and does not produce carbon monoxide, which is poisonous.

alkenes

A hydrocarbons with one or more carbon to carbon double bonds

What is the general formula for alkanes?

CnH2n+2.

endothermic reaction

A reaction that takes in energy from the surroundings, causing a temperature decrease.

exothermic reaction

A reaction that releases energy to the surroundings, causing a temperature increase.

activation energy

The minimum energy required to initiate a chemical reaction.

Alkynes

contains triple bonds

What are fuels typically composed of?

hydrogen, carbon, and sometimes sulfur.

How to calculate moles of C3H8 in 50 kg?

Moles of C3H8 = 50,000 g / 44.1 g/mol ≈ 1131.3 moles.

What is the empirical formula?

The empirical formula shows the simplest ratio of atoms present (e.g., C2H6 would be CH3).

What is a condensed formula?

A condensed formula is written according to the structure of the compound (e.g., ethene is H2C=CH2).

methyl branch

A compound with one-carbon branch in a hydrocarbon chain, indicated by placing a number before it to show its position.

How do you indicate a double bond in alkenes?

Double bonds in alkenes are indicated by writing the number of the carbon where the double bond is located (e.g., but-1-ene, but-2-ene).

dimethyl compound

A compound that has two methyl branches, indicated by two numbers before the 'methyl' with commas to show their positions.

trimethyl

refers to a compound with three methyl branches, indicated by three numbers before the 'methyl' with commas to show their positions.

alcohols

contain an OH group in one of their branches instead of just hydrogen.

How much CO2 will be produced if 50 kg of C3H8 burns completely in oxygen?

C3H8+ (5)O2 → (4)H2O + (3)CO2

1. Calculate the moles of C3H8:

   • The molar mass of C3H8 (propane) is approximately 44.1 g/mol (just add up the atomic masses)

   • Convert 50 kg to grams: 50 kg = 50,000 g.

   • Moles of C3H8 = mass (g) / molar mass (g/mol) = 50,000 g / 44.1 g/mol ≈ 1131.3 moles.

2. Use the balanced equation:

   • The equation C3H8 + (5) O2 → (4) H2O + (3) CO2 indicates that 1 mole of C3H8 produces 3 moles of CO2.

   • Therefore, moles of CO2 produced = moles of C3H8 × 3 = 1131.3 moles × 3 ≈ 3393.9 moles.

3. Calculate the mass of CO2 produced:

   • The molar mass of CO2 is approximately 44.01 g/mol.

   • Mass of CO2 = moles × molar mass = 3393.9 moles × 44.01 g/mol ≈ 149,971 g or approximately 149.97 kg.