Bronsted-Lowry acids and bases

Which species can behave as a Brønsted–Lowry acid in aqueous solution?

This question is about esters.

Figure 4 shows an incomplete mechanism for the reaction of an ester with aqueous sodium hydroxide.

Add three curly arrows to complete the mechanism in Figure 4.

Name the type of reaction shown in Figure 4.

Deduce the role of the CH₃O⁻ ion in step 3 shown in Figure 4.

A triester in vegetable oil reacts with sodium hydroxide in a similar way.

Give a use for a product of this reaction.

Which can not function as a Brønsted-Lowry acid?

This question is about fuels.

The petrol fraction obtained from crude oil can be used as fuel in cars.

State the meaning of fraction, as used in the term petrol fraction.

Hexadecane (C₁₆H₃₄) can be cracked at high temperature to form petrol.

Complete the equation to show the cracking of one molecule of hexadecane to form hexane and cyclopentane only.

Give the name of a catalyst used in this cracking reaction.

Carbon dioxide is formed when petrol is burned. Carbon dioxide acts as a greenhouse gas when it absorbs infrared radiation.

Give a reason why carbon dioxide absorbs infrared radiation.

Compound Z (HOCH₂CH₂NH₂) can be used to remove carbon dioxide from the mixture of waste gases produced in some power stations.

Figure 1 shows part of a suggested mechanism for the reaction of Z with carbon dioxide.

Draw two curly arrows to complete the mechanism in Figure 1.

Name compound Z (HOCH₂CH₂NH₂)

Deduce the role of Z in step 2 of the mechanism.

HOCH₂CH₂NH₂ can be represented as XNH₂ [HOCH₂CH₂NH₃]⁺ can be represented as [XNH₃]⁺

Draw the shape of XNH₂ and of [XNH₃]⁺

State whether the H–N–H bond angle in XNH₂ is greater than, the same as, or smaller than that in [XNH₃]⁺

Explain your answer.

Shape of XNH₂ Shape of [XNH₃]⁺

Bioethanol is used as an alternative to fossil fuels.

This statement appeared on a website.

“The fact that bioethanol is a carbon-neutral fuel outweighs the environmental disadvantages of producing bioethanol.”

Evaluate this statement.

In your answer you should include:

• an outline of how bioethanol is produced

• relevant equations

• analysis of the environmental impacts.

When anhydrous aluminium chloride reacts with water, solution Y is formed that contains a complex aluminium ion, Z, and chloride ions.

Give an equation for this reaction.

Give an equation to show how the complex ion Z can act as a Brønsted–Lowry acid with water.

Describe two observations you would make when an excess of sodium carbonate solution is added to solution Y. Give an equation for the reaction. In your equation, include the formula of each complex aluminium species.

Equation

Aqueous potassium hydroxide is added, until in excess, to solution Y.

Describe two observations you would make. For each observation give an equation for the reaction that occurs. In your equations, include the formula of each complex aluminium species.

Equation 1

Equation 2

The nitration of benzene uses a nitrating mixture of concentrated nitric acid and concentrated sulfuric acid.

Which statement is correct?