Which of the following solutions has the higher molarity? (a) 10 ppm KI in water or 10,000 ppb KBr in water

Video transcript

Hello everyone today, we are the following problem determine which has the higher molar itty in water. 30 parts per million sodium chloride or 40,000 parts per billion sodium fluoride. So the first thing we want to do is we want to Make note of the molecular weights for both the sodium chloride and sodium fluoride. So the sodium chloride, if you take sodium and chlorine from the periodic table and you add their masses up, you will get 58.44 g per mole. And if you do the same thing with the mass of sodium and the massive flooring, you're going to get 41.99 g per mole. And so we'll hang onto these two numbers for later. We didn't want to assume a couple of things. 1st, we want to assume that the density For each solution is going to equal one g per middle leader. And we're also going to want to assume that the volume for each solution is going to be one leader and one leader is equal to 1000 militia leaders. And so we're gonna keep note of both of these for a leader measure. Next, before we determine which one of these is has the higher morality, we're going to find the mass for each solution. So we're gonna have our mass of each solution. We're going to find that by taking our volume which is 1000 ml and multiplying that by density, which is one g per middle leader. And when our units and ml canceled out, we're going to have 1000 g. And so now we can work with both of these products. So to find the malaria for our sodium chloride, what we're going to do. So you're going to set up the following problem or the following equation, we're going to have 30 parts per million Equalling, we're going to have our mass of sodium chloride on the top. And they were gonna have divided that by 1000 g for the solution in total. And then we're gonna multiplied by a conversion factor of 10 to the sixth. And that 10 to the six is actually equal to one million. And that is that we can get rid of our parts per billion on the left hand side of the equation. And so when we simplify this equation, we're going to get that the mass of our sodium chloride that we are working with is equal to 0.03 g. And from that we can solve for our polarity. And so how do we do that? Well, charities and units of moles per liter most per liter. So we're going to take the moles, which we can find by doing the following. We can take our mass of sodium chloride, 0.03g. We're going to take the molar mass that we found from earlier, which is 58 .44 g per mole. And our units of grams will cancel out. And then we have the one leader that we assume we're working with. And when we simplify this, We're going to get 0. Moeller, that's going to be for sodium chloride. So we'll hang onto that number for later. Next we need to find the polarity of sodium fluoride. And so we're going to start with 40,000 parts per billion equaling the mass Of sodium fluoride over the 1000 g. And at this time we're gonna multiply by the conversion factor 10 to the ninth. We're just one billion. And that is to get rid of the billion on the left hand side of the equation. And so when we simplify this equation, we will end up with a mass for sodium fluoride as 0.04 g. So we'll hang on to that number there, We can use that to then find the polarity similarly to how we did with sodium chloride. So we similarities and units of moles per liter. So we're gonna take our 0.04 g and divide that by the molar mass of sodium fluoride which was 41.99 g per mole. And then we're going to divide by the one leader And we get 0.00095 molar. And so if we were to compare these two, the number with the highest modularity is going to be 0.00095 Molar. And that is going to come from our sodium fluoride. So our overall answer is going to be sodium fluoride. And with that we've answered the question overall, I hope that this helped, and until next time.