Question

A sample of 10 g coal yields 1 g of moisture, 2 g of ash and 5.6 g of volatile matter. The percentage of volatile matter content of the coal on dry ash-free basis is ________. \text{[round off to 1 decimal place]}

Hint:

To calculate the percentage of volatile matter on a dry ash-free basis, subtract the moisture and ash content from the total weight and then use the formula to find the percentage.

Answer 1

Correct Answer: 80

To find the percentage of volatile matter on a dry ash-free basis, we first calculate the weight of the dry, ash-free material. The total weight of the sample is 10 g. The weight of moisture and ash are given as 1 g and 2 g, respectively. The weight of the dry, ash-free material is: \[ \text{Dry, ash-free material} = 10 - 1 - 2 = 7 \, \text{g}. \] The percentage of volatile matter on the dry ash-free basis is calculated as: \[ \text{Percentage of volatile matter} = \frac{\text{Weight of volatile matter}}{\text{Weight of dry ash-free material}} \times 100 \] Substitute the values: \[ \text{Percentage of volatile matter} = \frac{5.6}{7} \times 100 = 80.0%. \] Thus, the percentage of volatile matter on the dry ash-free basis is \( \boxed{80.0} % \).