What does an acid + a base create?
2 Answers
Acid + base = salt + water
Explanation:
This is called a neutralisation reaction. Acids and bases react, if they are in the right proportions, to neutralise one another.
For example:
in this case the salt is sodium chloride, common table salt, but that's not always what happens:
In this case nitric acid reacts with potassium hydroxide to give potassium nitrate (the salt). You can see that in both cases, an acid plus a base has given a salt plus water.
In general, the reaction forms the conjugate base of the acid and the conjugate acid of the base.
GENERIC ACID/BASE REACTION
If we suppose we had a generic acid
#stackrel("acid")overbrace("HA") + stackrel("base")overbrace("B") rightleftharpoons stackrel("conjugate acid")overbrace("BH"^(+)) + stackrel("conjugate base")overbrace("A"^(-))# where the equilibrium arrows are skewed towards the products if the
#"pKa"# of#"HA"# is lower than that of#"BH"^(+)# , or skewed towards the reactants if the#"pKa"# of#"HA"# is higher than that of#"BH"^(+)# .
As you can see, we have that:
- The conjugate base of an acid is the acid with one less proton.
- The conjugate acid of a base is the base with one more proton.
And if you aren't familiar, the
HOW DO I KNOW WHICH WAY IT'S SKEWED?
Remember (or recognize) that the equilibrium lies on the side of the weaker acid, i.e. the acid with the stronger bond with the proton (
For instance,
#stackrel("acid")overbrace("HC"_2"H"_3"O"_2) + stackrel("base")overbrace("NH"_3) -> stackrel("conjugate acid")overbrace("NH"_4^(+)) + stackrel("conjugate base")overbrace("C"_2"H"_3"O"_2^(-))#
#"pKa" ~~ "4.74" color(white)(--a--) "pKa" ~~ "9.4"#
What happens is that since the
A trick to figure out to what extent is to do the calculation
#color(blue)((["BH"^(+)])/(["HA"]) = 10^("pKa,product acid" - "pKa,reactant acid"))# .
From that you would figure out that this reaction is favored by about