Embedded Files
Decomposition upon Heating
Chemical Property: Decomposition Upon Heating
Evaporation to dryness involves strong heating, where all the solvent is boiled away to leave behind the solute as the residue in the evaporating dish. However, strong heating can cause the properties of the dissolved substance to change.
#Issue 1: Decomposition Upon Strong Heating
Strong heating of some substances (e.g., sugar), can cause a chemical reaction known as decomposition to occur.
Decomposition is the process in which a substance is chemically broken down into two or more simpler substances
E.g., decomposition of sugar
sugar → carbon + water
C12H22O12 → 12 C + 11 H2O
In the case of decomposition upon heating, pure solute is not able to be obtained.
Issue #2: Dehydration of Crystals
Some substances, like copper (II) sulfate, exist in the form of hydrated crystals. Strong heating can cause the loss of water from these crystals, resulting in an anhydrous salt.
In these cases where strong heating can cause a change in the chemical properties of the dissolved solid, crystallisation is needed to obtain a pure sample of the solid from a solution.
Page updated
Report abuse