| 2.0 g of a sample contains mixture of \[Si{{O}_{2}}\]and\[F{{e}_{2}}{{O}_{\text{3}}}\]. On very strong heating, it leaves a residue weighing 1.96 g. The reaction responsible for loss of mass is given below. |
| \[F{{e}_{2}}{{O}_{3}}(s)\to F{{e}_{3}}{{O}_{4}}(s)+O(g),\](unbalance equation) |
| What is the percentage by mass of \[Si{{O}_{2}}\] in original sample? |
A) 100%
B) 20%
C) 40%
D) 60%
Correct Answer: C
Solution :
| [c] \[3F{{e}_{2}}{{O}_{3}}(s)\ to 2F{{e}_{3}}{{O}_{4}}+\frac{1}{2}{{O}_{2}}\] |
| 480 g \[F{{e}_{2}}{{O}_{3}}\] provide \[16g\,{{O}_{2}}\]. |
| For loss of \[0.04\text{ }g\text{ }{{O}_{2}}\ to 0.04\times \frac{480}{16}=1.2g\,F{{e}_{2}}{{O}_{3}}\] |
| % by mass of \[Si{{O}_{2}}=\frac{0.8}{2.0}\times 100=40%\]% |
You need to login to perform this action.
You will be redirected in
3 sec
