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Use of acids

Why do some reactions require HCl and some require H2SO4. Assuming we only care about the main product, shouldn't a reaction work if it is H+.

Also why does a reaction care if it is conc. or dil. H+, again a lot of dil. provides the same amount of H+ as a little conc, right? so why conc. and dil?

Also dil H+ is the same as H+ (aq) right?

These markschemes are pissing me off when they say 'NOT HCl' or 'NOT H2SO4'.

Also, why do some markschemes say NOT 'HCl' but allow Hydrochloric acid?! What is the difference between Hydrogen Chloride, and Hydrochloric acid... their state?

Grrrrr.

Reply 1

hungry_hog

dil vs conc acid will effect the rate of reaction

the reason they say not HCl is probably due to confusion with the discrete molecule. But can't see anything wrong with HCl (aq)

Reply 2

charco

Study Forum Helper

Possible reasons:
1. certain acids may interfer if there is an interaction between the negative ion and the reagent.
2. maybe there is more than one product possible due to another mode of action of the acid - eg sulphuric acid can also behave as a dehydrating agent and an oxidising agent (as can nitric acid)
3. HCl is more volatile when the temperature rises - the HCl gas may be lost.

You need to give specific examples and each can be dealt with logically.