The density of a 20.0% by mass ethylene glycol (C₂H₆O₂) solution in water is 1.03 g/mL. Find the molarity of the solution.

Video transcript

Hey everyone. So today we are asked to calculate the polarity of a 70% weight by weight per chlorate acid solution in water. And were given that the density of the solution Is 1.67 g per mil a leader. So for this question we need to use the polarity formula polarity. And using the information given within the question, we can find the two values that we need for this. We can find the moles of solute or h C L 04 folkloric acid and our leaders of solution, leaders of solution. So to start off for the sake of this problem, we can assume that we have 100 g of total solution Because then 70% of this, our 70% weight by weight of preclearance acid. It's just simply 70 g of ACL 04, it just makes their calculations a lot easier. And using the periodic table, we can determine that the molar mass of is 100 . grams per mole. So to then convert the grams the mass of hcl four that we have two molds of folkloric acid. We can use some quick stoking metric conversions before multiply this by the inverse smaller mass. One mole over 100. cramps. And that will leave us with 0.69 grams. Sorry malls of Hcl 04 of pro clark acid. Now to find the leaders of solution, we need to use the density rho Which is 1. grams for milliliters. Right? And remember that density is nothing more than mass by volume. So to find the volume. Therefore the volume is equal to the mass by the density. And we can use the mass that we assumed earlier or 100 g of solution here as well. So let's calculate that. So this will be 100 g per one point or sorry, divided by air. My bad 1.67 grams per milliliter. And our grams will cancel out. And we'll be left with an answer of 59 point 88 milliliters. But we're not done here. We need our volume and leaders so we can recall that we have 10 to the negative 3rd leaders For every one millim. So we can actually multiply this by our volume or sorry, volume that we just calculated 59.88 mm And will reach a value of 0. L. So bringing this back to our polarity, the polarity is equal to 0. 968 more each. Cielo four divided by 0.05988 L of solution Which will give us an answer of 11.6 molar 11.6 Molar