7 2 reactions of alkenes and alcohols

The general formula for alkenes is CnH2n.

The formula of pentene is C5H10.

The double carbon bond (C=C) is the functional group in alkenes.

Alkenes are named using the same system as alkanes, with the suffix "-ene" instead of "-ane".

The name and structure of the first alkene is ethene, CH2=CH2.

An alkene is a hydrocarbon compound containing at least one carbon-carbon double bond.

A double bond is a covalent bond formed by sharing two pairs of electrons between atoms.

An unsaturated compound contains two fewer hydrogen atoms than the alkane with the same number of carbon atoms.

The name of the compound is propene.

The displayed formula of ethene is:

Butene is the name of the alkene with the formula C4H8?

The products of complete combustion of alkenes are carbon dioxide and water.

The smoky flame when alkenes burn is caused by incomplete combustion producing soot (carbon).

False. ** Alkenes often undergo incomplete** combustion in air due to their higher carbon to hydrogen ratio.

The possible products of incomplete combustion of alkenes are carbon monoxide, water, and carbon (soot).

Incomplete combustion is the reaction of a fuel with insufficient oxygen, producing carbon monoxide and/or carbon (soot) along with water.

True. Higher alkenes are more likely to produce soot when burning.

The symbol equation for the complete combustion of butene is: C4H8 + 6O2 → 4CO2 + 4H2O

For complete combustion to occur, there must be excess oxygen available.

The equation for the incomplete combustion of butene to form carbon and water is: C4H8   + 2O2    →   4C  +  4H2O

The equation for the incomplete combustion of butene to form carbon monoxide and water is: C3H6   + 3O2    →   3CO  +  3H2O

The reaction between bromine and propene is an example of an addition reaction.

An addition reaction is a reaction in which atoms of a simple molecule add across the carbon-carbon double bond so that the double bond becomes a single carbon-carbon bond.

In an addition reaction, only one product is formed

The colour change for the following reaction is orange to colourless.

When alkenes undergo addition reactions with hydrogen, an alkane is formed.

When alkenes undergo addition reactions with steam, an alcohol is formed.

The reaction between alkenes and steam is also called a hydration reaction.

True. In the reaction between ethene and steam, ethanol is produced.

True. Halogenation of alkenes occurs readily at room temperature.

Alcohols are named using the same system as alkanes and alkenes, with the final 'e' being replaced with 'ol'.

The name and formula of the first alcohol is methanol, CH3OH.

The name of the alcohol is butanol.

The name of the alcohol is ethanol.

False. The -OH group in alcohols is not the same as the hydroxide ion (OH⁻).

The molecular formula for ethanol is C2H5OH.

The conditions for fermentation to produce ethanol are a temperature between 15 and 35°C and the absence of oxygen.

The first four alcohols are commonly used as fuels. Methanol and ethanol are also used extensively as solvents.

The completed balanced symbol equation for the combustion of ethanol is: CH3CH2OH + 3O2 → 2CO2 + 3H2O

Hydrogen gas is formed when methanol reacts with sodium.

A carboxylic acid is formed when alcohols react with an oxidising agent.

The molecular formula of ethanoic acid is CH3COOH.

The name of the following carboxylic acid is propanoic acid.

The functional group of carboxylic acids is -COOH.

When carboxylic acids react with metal carbonates, a salt, water, and carbon dioxide gas are produced.

When ethanoic acid and magnesium carbonate react they form magnesium ethanoate, water and carbon dioxide.

To test for the gas produced when a carboxylic acid reacts with a metal carbonate:

Ethyl ethanoate is an ester.

The name of the following compound is ethyl ethanoate.

Carboxylic acids dissolve in water to form acidic solutions with pH values less than 7.

Carboxylic acids are weak acids.

False. Carboxylic acids only partially ionise in water.

The completed equation for the ionisation of propanoic acid. CH3CH2OOH ⇌ H+ + CH3CH2COO–

True. The strength of an acid is related to its degree of ionisation in water.

True. The pH of a weak acid will be higher than the pH of a strong acid, if their concentrations are the same.

The ionisation of a carboxylic acid is a reversible reaction.