Household hydrogen peroxide is an aqueous solution containing 3.0% hydrogen peroxide by mass. What is the molarity of this solution? (Assume a density of 1.01 g>mL.)

Video transcript

Hey everyone today, we're being asked to calculate the polarity of a solution that is 13.5% sodium chloride by mass. So right off the bat we can see that we're going to need to use the malaria the equation And the values given the problem to find two separate values Or two separate quantities. We need to find the molds of salute, which in this case is sodium chloride or N A C. L. And the total volume in liters of solution, which in this case will be water. It is an obvious solution. So first things first, we'll go ahead and start finding the molds of N A C L. So because they don't have any other concrete values given in the question other than the% 13.5%. We can go ahead and make some assumptions for the sake of our calculations. So we can assume that we have 100 g of solution of water. What this means is that 13.5% of that? or 13.5 g will be sodium chloride. So we can use this value of the mass of sodium chloride present in the solution to go ahead and find how many molds of sodium chloride we have And we can save this value. This assumed value of 100 g for a little bit later. So let's go ahead and start our conversions. We have 13.5 g of N A C L. To convert this to moles. We can multiply by the inverse of the Molar mass. Within this case is 58.44 g Permal. And we can find these values using the periodic table. 58.5. Sorry, 44 g N A C L. So our g terms will cancel. And we will be left with 0. moles of N A C L. So that is our most however, to find the volume, we require a few steps. Now the question says to use the density of water as the density of the solution. Now the density of water is one g per mil a leader. And we've assumed In the first part that we have 100 g of solution. So this means that if we want to convert grams milliliters we multiply by the inverse of the density. So 100 g of water times one millimeter divided by one g. Are crimes will cancel out and we will have 100 ml of water. Pretty simple. However, we're not done yet. See we need our volume in leaders and if we recall for every one And we'll just write this out here 100 ml for every one millimeter. We have we have 10 to the negative three leaders. This is our conversion factor. So our middle leaders will cancel out and we will be left with 0. L of water. So now that we have our volume, we can go ahead and plug it back into our polarity equation. Some polarity is equal to 0.231, Jeez 231 moles have an A c l divided by 0. L of water. And this will give us a final value of 2. holder. Therefore The polarity of a solution that is 13.5% NACL by mass. It's 2.31 molar. I hope this helps. And I look forward to seeing you in the next one.