How to remove K2SO4 and K2CO3 mixed in KCl

How to remove K2SO4 and K2CO3 mixed in KCl

Dissolve with water, and then add excessive calcium chloride solution, which will produce calcium sulfate and calcium carbonate precipitation, and form potassium chloride, and then add carbon dioxide to excess calcium ions.

In that chemical equation ca (oh)2+co2=caco3, Why when calcium hydroxide is introduced into co2, co2 does not change into carbonic acid and then reacts with him, but reacts with him directly In that chemical equation ca (oh)2+co2=caco3, Why is it that when calcium hydroxide is introduced into co2, co2 does not change into carbonic acid and then reacts with reacts with him directly

You're right.
When CO2 is introduced into the solution, CO2 is first reacted with H2O to form H2CO3, then H2CO3 reacts with Ca (OH)2.
(1) CO2+ H2O = reversible = H2CO3
(2) Ca (OH)2+H2CO3=CaCO3 2H2O
Reaction (1) consumes 1 H2O and 2 H2O is formed in reaction (2). Finally,1 H2O is formed
Therefore, the total reaction equation is:
Total Ca (OH)2+CO2=CaCO3↓+H2O
In fact, the reaction of dry Ca (OH)2 solid and CO2 gas is very slow at normal temperature and can be considered as non-reaction at normal temperature.
It can also be seen from this point that the CO2 in the solution can react with Ca (OH)2 only when it is changed into H2CO3.
In addition, quick lime is added to the coal for desulfurization to prevent the SO2 gas generated by sulfur combustion from escaping into the air and polluting the air. This reaction can only occur when the temperature is very high. The reaction is as follows:
(1) CaO+SO2=high temperature=CaSO3
(2)2CaSO3+O2=2CaSO4
Definition of metathesis reaction: A reaction in which two compounds exchange components to form two other compounds.
Expressed as AB + CD = AD + CB
(1) Therefore, Ca (OH)2+CO 2=CaCO 3 H 2O is not a metathesis reaction.
Ca (OH)2+H2CO3=CaCO3 2H2O is metathesis reaction
It can be concluded that the reaction of all acidic oxides and bases is not a metathesis reaction.
(2) The reaction between basic oxide and acid is a double decomposition reaction, which conforms to the general formula
For example: CaO+2HCl=2CaCl+H2O
The CaO does not need to combine with H2O to form Ca (OH)2 and then react with HCl. Instead, CaO reacts with HCl directly and exchanges components with each other, which is consistent with the characteristics of metathesis reaction.
It can be concluded that the reactions of all basic oxides and acids are metathesis reactions.