Question

In chemistry, when you are solving for average atomic mass should you wait until the very end of the whole problem to round for sig figs, round seperately for the multiplication and addition or keep track as you go and round at the end?

Answer 1

When solving for average atomic mass in chemistry, it is generally recommended to keep track of significant figures throughout the problem and round at the end. This approach ensures that you maintain the highest level of accuracy and minimize rounding errors.

Here's a step-by-step guide on how to handle significant figures when calculating average atomic mass:

1. Calculate the mass contribution for each isotope: Multiply the mass of each isotope by its relative abundance. At this stage, use the given masses and abundances with the appropriate number of significant figures.

2. Sum the mass contributions: Add up the mass contributions of all the isotopes. At this point, don't round the intermediate values; instead, keep all the significant figures.

3. Calculate the total abundance: Sum the relative abundances of all the isotopes.

4. Calculate the average atomic mass: Divide the sum of the mass contributions by the total abundance.

5. Round the average atomic mass: Once you have obtained the average atomic mass, round the final result to the appropriate number of significant figures based on the given data or the least precise measurement in the problem.

By rounding at the end, you ensure that any rounding errors that occur during intermediate calculations are minimized and that you have the correct number of significant figures in the final result.