Question

$ 15.3g $ of element $ X $ (atomic mass $ = 27 $ ) combines with $ 13.6g $ of oxygen to be oxide.
(A) Express this in moles
(B) What is the simplest formula for the oxide.

Answer 1

Hint: to calculate the simplest formula for the oxide we first need to find to number of moles by using the formula $ n = \dfrac{m}{M} $ where $ n $ is number of moles $ m $ is given mass and $ M $ is molecular mass. Then multiply the percentage of each oxygen with mole number of each oxide by the number of oxygen in the oxide formula

Complete answer:
A)So in order to calculate the number of moles of any substance present in the sample, we simply divide the given weight of the substance by its molar mass. Mathematically, $ n = \dfrac{m}{M} $ Where $ n $ is the number of moles, $ m $ is the given mass and $ M $ is the molar mass.
Number of moles of $ X = \dfrac{{15.3}}{{27}}g $
Number of moles of $ O = \dfrac{{13.6}}{{16}}g $
B)There are two basic steps we need to follow to calculate the simplest formula for oxide.
Divide the weight percentage of each oxide by the formula weight of that oxide.
Multiply the resulting mole number of each oxide by the number of oxygens in the oxide formula.
 $ \Rightarrow {X_{0.57}}{O_{0.85}} $
 $ \Rightarrow {X_{\dfrac{{O.57}}{{0.57}}}}{O_{\dfrac{{0.85}}{{0.57}}}} $
 $ \Rightarrow {X_1}{O_{1.5}} $
 $ \Rightarrow {X_{1 \times 2}}{O_{\dfrac{3}{2} \times 2}} $
 $ \Rightarrow {X_2}{O_3} $
 $ 2 $ moles of $ X $ reacts with $ 3 $ moles of oxygen.

Additional Information:
The oxides are an important category of technical ceramics. The oxides are used in the following forms: pure oxides, alloys, multi‐oxides, and composites. The applications of advanced ceramics in mechanical engineering, including in the aerospace, automotive and defense industries.

Note:
The electropositive character of the oxide's central atom will determine whether the oxide will be acidic or basic. The more electropositive the central atom the more basic the oxide. The more electronegative the central atom, the more acidic the oxide.