a) decomposition / catalytic cracking

Notice that the reactant C5H12(pentane) contains 5 C atoms and 12 H atoms.

But on the product side, we only see C3H6 (propene, which only contains 3 C atoms and 6 H atoms) and H2 (hydrogen gas, which contains 2 H atoms)

That's only a total of 3 C atoms and 8 H atoms. In order for the equation to be balanced, the other 2 C atoms and 4 H atoms must be in the other product Y.

Molecular formula of Y = C2H4 (ethene/ethylene)

Structural formula of C3H6 :

H.........CH3
..\......./
.. C=C
.. /......\
H..........H


Ignore the dots as they are only used for spacing . The slant lines are the single bonds.

(the app doesn't allow multiple blank spaces to be typed and would cause all the letters and symbols to be grouped together)

Do note that the 3 is to be written in subscript

Lol, that was a very good try to draw the structure in the text box.

Ria, let me know if you need any further explanation.

Thank u so much

Ya haha

Cracking is the only process which allows a long-chained hydrocarbon to be broken down into smaller hydrocarbons and/or hydrogen gas. Typically, an alkane is broken down into smaller alkanes, smaller alkenes and/or hydrogen gas.

In the process of cracking, the total number of hydrogen and carbon on both sides remain unchanged, since atoms are neither created nor destroyed (law of conservation of atoms).

As such, we need to account for the “missing” carbons and hydrogens on the products side of the equation, which will become our wanted compound of C2H4, which is called ethene.

The structural formula to draw is just a diagram representation of all the atoms present in the molecule and all the covalent bonds joining the atoms together.

Thank u!!

Would u maybe be able to help me with my latest qn?