Question

Which one of the following is not a balanced equation?

    A.  4Na (s) + O2 (g) → 2Na2O (s)
    B.  2Mg (s) + O2 (g) → 2MgO (s)
    C.  C3H8 (g) + 5O2 (g) → 3CO2 (g) + 4H2O (g)
    D.  C3H8 (g) + O2 (g) → CO2 (g) + H2O (g)

Answer 1

The answer is D.

Explanation:

• If you give a look on the equation D, you can see that though in the left side, there are `3` Carbon atoms, in the right side there is `1` Carbon atoms.

Answer 2

Surely it is `D.`?

Explanation:

A stoichiometrically balanced equation balances (i) mass, and (ii) charge. And we practise stoichiometry all the time when we pay cash and receive change for goods...and we also practise it when we pay electronically: for every debit item (your grocery bill), there must be a corresponding credit...i.e. cash transferred from your account.

Chemical equations are simply debit and credit writ large. For every reactant particle there must be a product particle. For every electronic charge in the reactants, there must be a corresponding reactant charge.

And for `D` we have proposed a whack combustion of propane...

`underbrace(C_3H_8(g) + O_2(g))_"76 g" rarr underbrace(CO_2(g) + H_2O(l))_("62 g")`

Clearly, mass is NOT conserved, and thus this cannot be accepted as a real chemical outcome....