Question

how to remember chemical reactions ?

Answer 1

Chemical equations can be thought of like prom, where your date leaves you to go dance with someone else.

Single replacement:

Cd + 2HCl ---> CdCl2 + H2

In this case, Cd walks over to 2H and kicks him/her out of the dance. Cd is now dancing with 2Cl and 2H is left alone. In single replacement reactions, one element is always left alone (in this case 2H is alone).

Double replacement:

3FeCl2 + 2Na3PO4 ---> 6NaCl + 3Fe(PO4)^2

Fe walks over to P4O and asks if he can switch dance partners. P4O agrees and switches his dance partner for another one. In double replacement reactions the first elements of both compounds switch places; in this reaction no one is left out of the dance.

Synthesis:

3Mg + 2N ---> Mg3N2

Two people at prom are alone and don't have dates. 3Mg goes over to 2N and asks her if he can dance with her. 2N accepts the invitation and both are now dancing happily. Synthesis reactions start with 2 elements and the end result is 1 compound.

Decomposition:

4H2O2 ---> 4H2O + 2O

4HO gets into a fight with 2O. The two break up and both of them are alone.

Combustion reactions can be symbolized by the prom story. But, since it's inappropriate, I will not use it for combustion reactions.

A water dragon drinks a chemical substance, inhales and exhales.

Combustion:

C4H + 4O ---> C2O + 4HO

A water dragon drinks C4H and 4O. When the dragon exhales it makes CO2 + 2H2O. Combustion reactions always end with Carbon dioxide, rarely a different gas, and water (H20).

Answer 2

but wont we get confused for other reactions since there are so many reactions

Answer 3

Best explanation ever! Thank you so much!