Question

A binary compound of nickel and oxygen contain 78.06% nickel by mass. In this stoichiometric or a stoichiometric compound. Explain?

Short answer

We are given with binary compound of nickel and oxygen which contain a certain amount of nickel by mass. To fond, whether it is a stoichiometric or non-stoichiometric compound involve

Step-by-step solution

Calculation of moles of Ni and O present in the sample.

The binary compound of nickel (Ni), Oxygen (O) contains 78.06% nickel by mass respectively.

The mass of elements present in 100.0g of the compound is

Ni = 78.06g

O = (100.0 – 78.06g) = 21.94g

The number of moles of each element present in the sample is

$$\begin{gathered} MolesofNi=78.06g\times \frac{1molNi}{58.69g} \\ =1.330mol \end{gathered}$$

$$\begin{gathered} MolesofO=21.94g\times \frac{1molO}{16.00g} \\ =1.371mol \end{gathered}$$

To find whether the compound is stoichiometric or non-stoichiometric

Non Stoichiometric compounds are chemical compounds with an elemental composition which cannot be represented by a ratio of well-defined whole numbers.

The ratio of the amount of the elements present in this compound is:

$\text{Ni:O = 1.330:1.371}$

Dividing each of the amounts by 1.330

$$\begin{gathered} \text{Ni:O =}\frac{\text{1.330}}{\text{1.330}}\text{:}\frac{\text{1.371}}{\text{1.330}} \\ \text{1:1.031} \end{gathered}$$

Here the empirical formula of the binary compound of nickel and oxygen is N:01.031, therefore, the compound is non-Stoichiometric.