Combustion and Organic Chemistry Quiz

What is the difference between complete and incomplete combustion of hydrocarbons? Write the word equations for both types of combustion using ethene as the hydrocarbon.

Answer explanation

Complete combustion of ethene (C2H4) produces carbon dioxide and water: C2H4 + 3O2 → 2CO2 + 2H2O. Incomplete combustion produces carbon monoxide and water: C2H4 + 2O2 → 2CO + 2H2O. The key difference is the products formed.

What is the general formula for alkenes?

Answer explanation

The general formula for alkenes is CnH2n, where n is the number of carbon atoms. This formula reflects the presence of at least one carbon-carbon double bond in the alkene structure.

How do you test for the presence of an alkene?

Answer explanation

To test for the presence of an alkene, you can use bromine water. If the solution decolorizes from brown to colorless, it indicates the presence of an alkene due to the addition reaction.

Write the equation for the oxidation of ethanol.

Answer explanation

The oxidation of ethanol (C2H5OH) can be represented by the equation: C2H5OH + O2 → CH3COOH + H2O. Ethanol is converted to acetic acid (CH3COOH) in the presence of oxygen.

What is the name of the ester formed when ethanoic acid reacts with ethanol?

Answer explanation

The ester formed when ethanoic acid reacts with ethanol is called ethyl acetate. This reaction is an example of esterification, where the hydroxyl group of the acid and the hydrogen of the alcohol combine, releasing water.

Why do carboxylic acids turn blue litmus paper red?

Answer explanation

Carboxylic acids are acidic in nature, releasing hydrogen ions (H+) in solution. This increase in H+ concentration causes blue litmus paper to turn red, indicating acidity.

What is the functional group of alcohols?

Answer explanation

The functional group of alcohols is the hydroxyl group (-OH). This group is responsible for the characteristic properties of alcohols, including their ability to form hydrogen bonds and their solubility in water.

Write the equation for the reaction of ethanoic acid with sodium carbonate.

Answer explanation

The reaction of ethanoic acid (CH3COOH) with sodium carbonate (Na2CO3) produces sodium acetate (CH3COONa), water (H2O), and carbon dioxide (CO2). The balanced equation is: 2 CH3COOH + Na2CO3 → 2 CH3COONa + H2O + CO2.

How do you test for alkenes?

Answer explanation

To test for alkenes, you can use bromine water. When an alkene is present, the bromine water will decolorize from brown to colorless, indicating a reaction has occurred.

Name the ester formed from ethanoic acid and ethanol.

Answer explanation

The ester formed from ethanoic acid (acetic acid) and ethanol is ethyl acetate. This occurs through a condensation reaction, where water is eliminated, resulting in the formation of the ester bond.