Question

a sample of an oxide of antimony (sb) contain 19.75 g of antimony combine with 6.5 g of oxygen . what is the simplest formula for the oxide

Answer 1

Explanation:

The given data is as follows.

      Mass of antimony = 19.75 g

      Molar mass of Sb = 121.76 g/mol

Therefore, calculate number of moles of Sb as follows.

                    Moles of Sb = $\frac{mass}{\text{molar mass}}$

                                         = $\frac{19.75 g}{121.76 g/mol}$

                                         = 0.162 mol

Mass of oxygen given is 6.5 g and molar mass of oxygen is 16 g/mol. Hence, moles of oxygen will be calculated as follows.

           Moles of oxygen = $\frac{mass}{\text{molar mass}}$

                                         = $\frac{6.5 g}{16 g/mol}$

                                         = 0.406 mol

Hence, ratio of moles of Sb and O will be as follows

                          Sb : O

                      $\frac{0.162}{0.162} : \frac{0.406}{0.162}$

                           1 : 2.5

We multiply both the ratio by 2 in order to get a whole number. Therefore, the ratio will be 2 : 5.

Thus, we can conclude that the empirical formula of the given oxide is $Sb_{2}O_{5}$.