Question

Webb has calculated the percent composition of a compound. How can he check his result?

Answer 1

Answer: second choice, by adding them to see if they total 100.

Explanation:

Percent composition of a compound tells the amount of each element taken 100 as a base of total amount, hence it adds up 100.

You can check it mathematically in this way.

Assume you have an amount n of a compound formed by many elements, and that the amounts of each element are n₁, n₂, n₃ ,....., were n₁ + n₂ + n₃ + ... = n.

When you find the percent of each element you find:

%n₁ = n₁ / n × 100

%n₂ = n₂ / n × 100

%n₃ = n₃ / n × 100 .... and so on.

Now, when you add all the percents you get:

n₁ / n × 100 + n₂ / n × 100 + n₃ / n × 100 + ... = [n₁ + n₂ + n₃ + ... ] / n × 100 =

= n/n × 100 = 1 × 100 = 100.

Therefore, the sum is 100, and this is a way to check your result.

Answer 2

Webb has calculated the percent composition of a compound. He can check his result by adding them to see if they total 100. That is the correct way in checking your results. The rest of the choices do not answer the question above.