Question 13

[jh2297474]

Iam confused regarding this questions.
they said two moles of diatomic gas P2 and four moles of diatomic gas Q2 and the product yields a triatomic
first of all i would have looked for something that looked like this
2 p2 + 4 q2 ---> 3 p4q8
i honestly dont understand the explanation it doesnt sounds right to me
please help

[mcat_premed3832]

The product in the equation that you wrote: 3 p4q8

The meaning of "3 p4q8 " is:

a) there are 3 molecules and each molecule is called p4q8

b) there are 4 p atoms in the molecule

c) there are 8 q atoms in the molecule

d) the molecule p4q8 has 12 atoms which is very different from the triatomic (3 atom) molecule described in the question.

Keep in mind the most famous diatomic (2 atom) molecules in chemistry: O2, Br2, Cl2, N2, etc.

Famous reaction between diatomic molecules:
Cl2 + H2 ==> 2 HCl

Using the logic you used in your reaction, I assume you would have thought that this would happen:

Cl2 + H2 ==> H2Cl2

which is impossible for many reasons. To understand this requires a content review for the MCAT which you can do with the Gold Standard or another comprehensive review guide.