ES - Hydrogen halides Flashcards
What is a hydrogen halide?
A halogen + hydrogen.
How many electrons do all the halogens have in their outer shells?
7
How many electrons does hydrogen have in its outer shell?
1
How can hydrogen halides be made?
Using ionic halides.
How can hydrogen halides be made by using ionic halides?
By adding a concentrated acid, to a solid, ionic halide.
Usually phosphoric acid.
Why can’t you always use sulfuric acid to make hydrogen halides?
As it is an oxidising agent so it can get involved in redox reactions.
Why can’t sulfuric acid be used to make hydrogen bromide or hydrogen iodide?
When sodium bromide or sodium iodide for example, react with sulfuric acid, the bromide/iodide ions are oxidised to make bromine/iodine gas because bromine and iodine are strong enough reducing agents to reduce sulfuric acid.
When are hydrogen fluoride and hydrogen chloride stable?
When heated.
When heated, hydrogen fluoride and hydrogen chloride are stable, what does this mean?
They won’t split up into hydrogen and halide ions.
When heated, what happens to hydrogen bromide and hydrogen iodide?
They’ll split - hydrogen bromide slightly and hydrogen iodide more so.
When heated, why do hydrogen bromide and hydrogen iodide split?
Because of the strength of the hydrogen-halide bonds being weaker.
What happens to the strength of the hydrogen-halide bonds as you go down group 7?
They get weaker.
Why do the hydrogen-halide bonds get weaker down group 7?
Because the halogen atoms get bigger down the group, meaning the bonding electrons are further away from the nucleus and shielded by more inner electron shells.
Are hydrogen halides acidic or alkali?
Acidic.
Hydrogen chloride, hydrogen bromide and hydrogen iodide all dissolve in water to form what?
Strong acids.
