3.1.7 neutralisation reactions

chem whatarethemechanismsofchemicalchange

Reactivity 3.1.7 - acids react with bases in neutralisation reactions

neutralisation reactions involve the reaction between ions and ions to form

in the reaction, an ionic compound called a salt forms.

the parent acid and parent base form a salt.

in neutralisation reactions, for every mole of that forms, 2 moles of bonds are formed. since bond formation is exothermic, the overall reaction is also exothermic, releasing energy.

for reactions between strong acids and strong bases, the enthalpy of neutralisation, expressed per mole of formed, is very similar

Warning

when acids react with reactive metals, there is also a salt formed as the hydrogen in the acid is replaced by the metal. however, there is no proton transfer, so this is a redox reaction.

eg:

note: and are soluble

eg:

these reactions can also be represented as ionic equations

bubbling is also known as effervescence

challenge questions

5. why do neutralisation reactions involving weak acids or weak bases give different values for their enthalpy of neutralisation compared with strong acids and bases?

in reactions between strong acids and bases, they are mostly ionised. however, in weak acids and weak bases, the majority of the substance is not ionised at the start of reaction, so energy is used to break bonds in ionising the reactants. the endothermic process reduces the net energy released when water forms.