5.4 Determine the percent compositions, empirical formulas, and molecular formulas. Student will be able to: Calculate the percent of each element in a compound. Distinguish the difference between the empirical formula and the molecular formula Use the percent composition to determine the empirical formula of a compound.

How do I determine the percent? Percent is generally described as the amount of part out of the whole The total amount of what you have divided by all of the material object. Mathematically, it is defined as one part in every hundred. If you have 70 questions out of 100 correct on a test, you have 70% correct. 70/100 = .7 *100 = 70%

How do you determine the percent composition of the a compound? Use your periodic table to determine the mass of each part of the molecule. Add the masses to determine the total mass of the compound. Divide the individual element masses by the total mass. The answer you have is the part out of the whole. Turn the answer in to a percent by multiplying the decimal number by 100 and add a percent symbol. The percent composition of water is 11% hydrogen and 88% oxygen. 2H has a mass of 1g*2 + O has a mass of 16g The total mass is 18g 2/18 = .11*100 = 11% 16/18 = .88*100 = 88% Watch the following video and answer practice calculating the percent composition. Copy a second example into your notebook.

https://www.youtube.com/watch?v=lywmGCfIUIA Copy at least 2 examples from this video into your notebook.

https://www. youtube. com/watch https://www.youtube.com/watch?v=wnRaBWvhYKY Explaining the difference between a molecular and empirical formula Molecular Formula – symbols and numbers which identify the number of atoms of each type in a balanced compound or molecule. Empirical Formula – The simplest whole number ratio of elements in a compound or molecule. Cut and paste the url above into a new browser to see a description of the empirical and molecular formula of butane and then pause the video and go to the next frame.

Notes Define molecular and empirical formula in your notebook. Copy the example of Butane into your notebook. Make sure you list his example step by step. Leave room for questions and clarifications to be added. Watch the examples after the first and add an example that identifies when the molecular and empirical are the same formula. Make a note explaining when multiple compounds have the same empirical formula. Watch the following video to see examples of calculating empirical formulas from the molecular formula https://www.youtube.com/watch?v=ucU5PD6W3Ik Copy several examples down in your notebook.

Calculating the molecular formula from percent composition https://www This can be a complicated process and needs to be calculated in steps. I have provided the URL for a video that will help learn this process. The speaker will provide you a list of steps as you go along. Listen the first time he describes the process and then rewind it to the steps being describe. Write the steps at the top of you page. Then re-watch the process and copy down the example they give you.