Knowledge Base Article
Article ID: 27312 [Last Updated11/27/2004 11:32:26 AM]
Summary:
How do I do the math in chemistry On Your Own 5.5?
Article:
You should really get a scientific calculator. Scientific calculators let you enter the numbers in scientific notation so that they take care of all of this for you. However, here is how it works. The equation boils down to:
(40.1) x (1.67 x 10^-24)/1000
If I take 40.1 x 1.67, I get 66.967. Thus, we have
66.967 x 10^-24 / 1000
Well, 1000 is really 10^3. Thus, we have
66.967 x 10^-24 / 10^3
When you divide numbers with exponents, you SUBTRACT thus,
10^-24 / 10 ^3 = 10^(-24-3) = 10^-27
Thus, the answer is
66.967 x 10^-27
That's not standard scientific notation, however. You need only ONE number left of the decimal for scientific notation. Therefore, I need to move the decimal to the LEFT one place. Doing that is like DIVIDING by 10. To preserve the value of the number, then, I need to MULTIPLY by 10 as well:
6.6967 x 10^-27 x 10
When you multiply numbers with exponents, you ADD the exponents:
10^-27 x 10 = 10^(-27 +1) = 10^-26
That makes the answer
6.70 x 10^-26