So we've talked about UNITS and CONSTANTS. Another basic of math in Chemistry is the use of SYMBOLS. Symbols are used to represent numerical values when you have an equation. That way, whenever you see a certain symbol, you can just plug a number into it. Here are some examples... Mass WHAT: This is the amount of a substance. Sometimes mass is confused with weight. Weight is a measure of mass based on how much gravity there is. Usually it is measured in grams. Speed of Light WHAT: Yes, "c" is a constant, but the letter "c" is also a symbol representing the Speed of Light in a vacuum. It is used in the equation E=mc2. Volume WHAT: The symbol for volume, usually measured in Liters. Total Pressure WHAT: We say this is the symbol of total pressure. That is all of the pressures added together. There are also values for the"partial pressures" in a system. Number of Moles WHAT: A mole measures the number of molecules, or atoms. So when you see the value "n", you know how many moles in a system. A mole is 6.02x1023 molecules or atoms. Molar Gas Constant WHAT: We already talked about that formula "PV=nRT" and that "R" was that constant. It's an important one to remember. That's why we talk about "R" in symbols. "R" is the Molar Gas Constant. Temperature WHAT: Remember PV=nRT, that's the one. Well that T stands for the temperature of the system. Relative Density WHAT: Density is how much things are packed together. Imagine a cube, one inch tall, one inch wide, and one inch long. If that cube is filled with styrofoam it is light. If it is filled with lead it is heavy. That is because lead has a higher density than styrofoam. Energy WHAT: We know it's kind of in the area of Physics, but E stands for energy. Remember the famous formula E=mc2? Well that E is Energy, and it equals Mass multiplied by the speed of light and then multiplied by the speed of light again. Molarity WHAT: This is the symbol for molarity. When Chemists talk about the concentration of substances dissolved in solution, they say it has a specific Molarity.