This question is about the halogens - AQA - GCSE Chemistry - Question 8 - 2020 - Paper 1

The boiling points of halogens increase down the group. This is mainly due to the increase in the relative molecular mass and size of the molecules. Larger molecules experience stronger London dispersion forces due to the greater number of electrons, requiring more energy to overcome these intermolecular forces. Consequently, as you move from fluorine to bromine, the boiling point rises.

The boiling point of a substance is a bulk property, meaning it relates to the collective behavior of many molecules rather than a single molecule. Therefore, stating that a single bromine molecule has a boiling point of 59 °C is incorrect as it overlooks the interactions between multiple molecules.

The gas / halogen is toxic, and performing the experiment in a fume cupboard prevents the inhalation of harmful gases, thus ensuring a safe working environment.

As you move down the group, the outer electrons are located in shells that are further from the nucleus. This distance reduces the nucleus's attraction for the incoming electron, making it harder for the atom to gain an electron. Additionally, increased shielding from inner shells decreases this attraction, leading to lower reactivity.

First, we find the moles of each component. The mass of iron is 4.48 g and that of chlorine is 8.52 g. Using their respective atomic masses, we calculate:

• moles of Fe = ( \frac{4.48}{56} = 0.08 )
• moles of Cl = ( \frac{8.52}{35.5} = 0.24 )

The ratio of moles of iron to chlorine is: ( \frac{0.08}{0.24} = \frac{1}{3} ) Thus, the simplest whole number ratio is 1 : 3.

The balanced equation for the reaction of iron with chlorine is: [ 2 \text{Fe} + 3 \text{Cl}_2 \rightarrow 2 \text{FeCl}_3 ] This shows that two moles of iron react with three moles of chlorine to form two moles of iron chloride.