Law of Multiple Proportions

by Jules Bruno
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in this video, we'll take a look at the law of multiple proportions. So here, in 18 04 the English chemist John Dalton originated the law of multiple proportions based on his atomic theory. Now it states that when two elements A and B former different compounds the mass of element be that combined with 1 g of a r a ratio of whole numbers. Now a definition like this isn't exactly cleared. So in order to better understand the law of multiple proportions, it's best to jump right into an example. So let's take a look here at this example. Question. Here, it says, illustrate how nitrogen monoxide, which is N. O. And nitrogen dioxide, which is N o. To obey the law of multiple proportions. Alright, So when we're given a question dealing with the law of multiple proportions, we're gonna follow these steps. So step one, we're gonna find the atomic masses of each elements from the periodic table. Nitrogen monoxide and nitrogen dioxide both contain nitrogen and oxygen. Nitrogen has an atomic mass of 14. g per mole. Oxygen has roughly atomic mass of 16 g per mole. What we do next is, we multiply together the number of each element with their atomic masses from the periodic table. Nitrogen monoxide is NL, which is just one nitrogen and one oxygen, so that comes out to 14.1 g per mole for N and 16.0 g per mole for oxygen. N 02 has in it one nitrogen and to oxygen's, so that would come out to 14.1 g per mold of N and 32 g per mole. Off Step three, we have to determine the mass ratios of each compound. So remember, when it comes to mass ratio, you should place the element with larger atomic mass on top. So for now, that would be the 16 g of oxygen for the every 14.1 g of nitrogen that comes out to 1.14 to as their mass ratio and then for no to that would be 32 g oxygen over 14.1 g nitrogen, so that will come out to 2.284 All right, so we know at this point we've figured out the mass ratios of both. Step four is what shows us that they follow the law of multiple proportions. Now step for if the law of multiple proportions is being followed in, the ratio of both mass ratios should give a whole number. So we're gonna place the larger mass ratio on top, divided by the smaller mass ratio on the bottom. When we do that, we get a value of two because we've gotten the whole number. That means that N. O and N 02 are following the law of multiple proportions. Basically, when you have two elements, they can combine in different ways to create different compounds. In N O, it's a 1 to 1 relationship, but in No. Two it's one nitrogen for every two oxygen's. So these are the steps you have to take in order. Determine if two compounds are following the law of multiple proportions.