Peter J. Mikulecky

Many calculations that you make in chemistry will involve unit conversions (for example, between meters and millimeters, or between meters and inches). Fortunately, you don’t need to know all possible unit conversions.Instead of memorizing or looking up conversion factors between all types of units, you can memorize just a handful of conversion factors and use them one after another, letting the units guide you each step of the way.

A conversion factor uses your knowledge of the relationships between units to convert from one unit to another. For example, if you know that there are 2.54 centimeters in every inch (or 2.2 pounds in every kilogram or 101.3 kilopascals in every atmosphere), then converting between those units becomes simple algebra.

To make it easier to work with extreme numbers, chemists turn to scientific notation, which is a special kind of exponential notation. A major benefit of presenting numbers in scientific notation is that it simplifies common arithmetic operations like multiplication and division. Multiplying in scientific notation To multiply two numbers written in scientific notation, you work out the coefficients and the exponents separately.

Chemists aren’t satisfied with measuring length, mass, temperature, and time alone. On the contrary, chemistry often deals in calculated quantities. These kinds of quantities are expressed with derived units, which are built from combinations of base units.Here are some examples: Area (for example, catalytic surface).

In chemistry, you can add and subtract extreme numbers by using exponential notation, and expressing your numbers as coefficients of identical powers of 10. To wrestle your numbers into this form, you may need to use coefficients less than 1 or greater than 10. Adding with exponential notation To add two numbers by using exponential notation, you begin by expressing each number as a coefficient and a power of 10.

When doing math in chemistry, you need to follow some rules to make sure that your sums, differences, products, and quotients honestly reflect the amount of precision present in the original measurements. That’s where significant figures come in.You can be honest (and avoid the skeptical jeers of surly chemists) by taking things one calculation at a time, following a few simple rules.

You have to have a good understanding of all sorts of problems to successfully get through a chemistry class. Many of those problems require you to follow a certain process to get to the right solution: Perhaps it’s a series of rules you must follow, a conversion you need to use, or a formula you have to apply.