dissolving any ammonium salts in water is endothermic reaction
14 Which of the following is an example of endothermic reaction?
Antara yang berikut, yang manakah contoh bagi tindak balas endotermik?
A Solid sodium hydroxide dissolved in distilled water
Pepejal natrium hidroksida dilarutkan dalam air suling
B Solid ammonium nitrate dissolved in distilled water
Pepejal ammonium nitrat dilarutkan dalam air suling
C Dilute hydrochloric acid added to silver nitrate solution
Asid hidroklorik cair ditambahkan kepada larutan argentum nitrat
D Dilute hydrochloric acid added to potassium hydroxide solution
Asid hidroklorik cair ditambahkan kepada larutan kalium hidroksida
An endothermic reaction means a chemical reaction that absorbs heat from the surroundings.
An exothermic reaction means a chemical reaction that releases heat to the surroundings.
Usually, most of the chemical reactions are exothermic. Here are some notes explaining exothermic reaction in detail and its examples:
(ignore the doodles haha I’m not sure why I drew them)
And for endothermic reaction:
We should memorize them (especially the endothermic ones) for examination purposes. So based on the notes, our answer is B, because B is an ammonium salt dissolved in water.
A is something like dilution, because we are adding water to the solid NaOH.
C falls under a precipitation reaction, where the precipitate formed is silver chloride:
HCl (aq) + AgNO_3 (aq) \rightarrow AgCl (s) + HNO_3 (aq)
(Heat of precipitation is under Form 5 Thermochemistry, this particular reaction is exothermic. If you have done it in your school laboratory, the temperature of the reaction mixture would increase when you start stirring the two solutions.)
D is a neutralization reaction, which falls under the exothermic category.
Hope this helps!
@D.B Thanks a million, the explanation is very clear, I appreciate it
@Sofiya_Ardina Thank you very much