Editing Dimensional Analysis Notes
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Dimensional Analysis or <b>Unit Factor Method, or Unit Canceling</b> are all names for the same concept. Simply put, the unit determine the math not the numbers. In other words, <br> <center><b>UNITS, NOT THE NUMBERS ARE KING</b></center><br> <center><b>Steps for Solving Mathematical Problems in Chemistry.</b></center><br> 1. Write down unknown (units and in more complex problems what substance)<br> <br> 2. Write down all known units including conversion factors<br> <b> A conversion factor is anything that allows you to go from one unit to another unit(s)</b>For example, density it is a conversion factor between mass (g) and volume (cm<sup>3</sup>).<br> <br> 3. Setting up the answer. (<b>If you are using equations, go to [[Set-Up for Equations Notes]]</b>)<br> *a. Look at units in answer to determine the first thing to write **If you answer has one units, then you start off with one units (if that one unit is in denominator, then you start with an unit in the denominator) **If answer has more than one unit, then you need to put down more than one known information ***For example if you answer is ft/s, then you start off with a distance term on the top and a time unit on the bottom *b. Starting with one unit, you then make parentheses ( ) and then a fraction where you put your known conversion factor to get to known unit to unit you are looking for in answer **Usually you don't have one conversion factor that will get you from your known unit to unit you are looking for. So you will have do have intermediate units. **If you have more than one unit, you one unit at a time and do another unit, <b>BUT</b> it is all on the same line (you don't break up the calculation.) *c. Once you have all the desire units, you are done with adding parentheses. <br> 4. Do math (same math rules apply as in sig fig (SF) and scientific notation (SN) section).<br> *Remember:<br> **Number must be in scientific notation if greater than 1E3 or less than 1E-3 **One number before answer in N+1 (one more sig fig as in answer), correct SN and units **Answer in correct SN, SF and units <br> 5. Check answer to see if has correct units (answering question asked) and number makes physical sense!!!<br> <br> -----------------<br> Example:<br> <br> <br> <br> <br> <br> <br> <br> <br> <br> <br> <br> <br> <br> <br> <br> <br> <br> <br> <br> <br> <br> <br> <br> <br> <br> <br> <br> <br>
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