I really don't understand word equations for acids,
salts and alkali's! How do u know wot is an acid, alkali or a salt
and how exactly do you write equations?
Acids have loosely bound Hydrogen and Alkalies are things that can
take the hydrogen away and turn it into water (by reacting it with
hydroxide)so the equation is usually: Acid + Alkalie => salt and
water. The simpliest one is HCl (Hydro-Chloric Acid) plus NaOH (Sodium
hydroxide) => NaCl (Sodium Chloride (salt)) and H2O (Water) HCl+NaOH
=> NaCl + H20. The tricky equations come in when you are dealing
with acids or bases that have different amounts of H or OH parts.
For example Hydrosulphuric acid has two H's (H2SO4) and so to react
this with Sodium Hydroxide you have to double-up the sodium hydroxide
part in order to balance it with the two H's. H2SO4 + 2NaOH => Na2SO4
+ 2 H2O (Sodium Sulphate and water - in this case the soduim sulphate
is the 'salt') All you have to do is balance the H's with enough
OH's in the simplest way and then remember to check that the rest
balances - in our second example we ended up with two waters instead
of one and ths sulphate gobbled-up the two sodiums. Last Example:
HydroChloric Acid and Calcium Hydroxide. Here, the Hydroxide has
two OH's and so we need two HydroChloric acids to make the equation
balance: 2 HCl + Ca(OH)2 => CaCl2 +2 H2O. Finally - remember that
just because you can write (for example) Na2SO4 it doesn't mean
that there are molecules around that have two sodium,a sulphur and
four Oxygens in it - It just means that, on balance, these are the
ratios that will be found of the atoms in the salt.
Brian
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