by Patrick Ford

Hey, guys, let's do another example about electric charge. Okay? Waterways. 1 kg per leader has a molecular weight of g per mole and has 10 electrons per molecule. Part A. How many electrons does two liters of water have? And part B. What charges? What charge do these electrons represent? So however many electrons we find in part A what is the charge of those electrons? Okay, so for part a first, what we wanna do is we want to figure out how to get from leaders, which is what we're given were given two liters of water to number of electrons. This will tell us how to solve the problem. We need to create a sort of map to the solution. Okay, let's start with leaders, right, Because that's what's given to us. What can we go to next? Well, we're told that there's a conversion between Kilograms and leaders that we can say for every leader of water it has a mass of 1 kg. So we know how to go from kill a grip from leaders. 2 kg. Next we have grams to moles. Now we don't have kilograms, two moles, but we know right away that 1 kg 1000 g So we can easily go from kilograms 2 g and then using the conversion, go from grams to moles. Now, our last conversion is electrons per molecule. We don't have our number of molecules yet. We haven't moles, but we could use alpha God Rose number to convert moles toe molecules. Now, using our last conversion factor, we can go from molecules to number of electrons. So this right here is our map. That's gonna guide us through this problem. Okay, so let's start doing these conversions. Two liters of water times 1 kg per leader is 2 kg. So our water has a massive 2 kg. Now right away. We know that that's equivalent to 2000 g. So we've done this step and this step. Now we need to go from grams to moles. Okay. 2000 g times g per one. Mole is about 111 moles. So we've done the next step. Now we need to go from moles. Two molecules using avocados number 111 moles times one mole per six times 10 to the 23rd molecules is times 10 to the 25 molecules of water. Okay, so we've done this step. The last step is simply to figure out how many electrons are represented by this much water. As many molecules of water. We know that it's 10 electrons per molecule, so it's very simple. We just multiply this number by 10 6.7 times 10 to the 26 electrons. Okay. And we followed our map successfully from leaders, which was given to us. Two electrons. Okay, now, part B. What charge does this amount of electrons represents? Well, each electron has a charge e the elementary charge, and we have some number of electrons in which we figured out in part a so multiplying. These together will tell us our total charge. Our number is 67 times 10 to the and the elementary charges. What? Remember, guys, you need to know this 16 times 10 to the negative 19. Coghlan's multiplying those. Together we get a total charge of 1.7 times 10 to the eight coolness. Okay,

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