Question

A sample of clay was partially dried and then analysed to 50% silica and 7% water. The original clay contained 12% water. Find the percentage of silica in the original sample.

Answer 1

In the partially dried clay the total percentage of silica + water = 57%. The rest of 43% must be some.

impurity. Therefore the ratio of wts. of silica to impurity =  50/43. This would be true in the original sample of silica.

The total percentage of silica + impurity in the original sample is 88. If x is the percentage of silica,