 So now what if you were asked to make up 250 mils of a two molar sodium chloride solution? So what you would have to do here is first determine how much moles of sodium chloride you will need in your 250 mil of solution. So one thing we are given we know the molecular weight of sodium chloride which is 58.44 grams per mole. So two molar NaCl basically means two moles of sodium chloride in one liter of solution. So we know that. Now what we need to determine therefore is how many moles of sodium chloride would be present in 250 mils of solution. So because molarity here represents moles per liter of solution, whatever volume that we're going to be using with regards to molarity has to be in liters. So we need to convert or 250 mils to liters. So therefore that would be 0.25 liters of sodium chloride. That's what we are trying to make. So we know that two moles of sodium chloride are present in one liter of the solution that we want to make. How much would be present in 250? Because we're not making one liter we want to make 250. I mean 0.25 liters of solution. So therefore our unknown here is x moles. So we're solving for moles first. So therefore moles of sodium chloride in 250 mils of solution would be two moles times 0.25 liters divided by one liter since we are cross multiplying and solving for x. In that case that is going to give me 0.5 moles. So therefore we know that 0.5 moles of sodium chloride are present in 250 mils of our solution. So because we have our weight because physically in order to make up the solution the ultimate here is to determine how much grams of sodium chloride do I need to make the solution. So we know how many moles will be present in the solution. So therefore what we need to do now is to solve based on that convert the moles to grams to determine how much grams we're going to need to add to our 250 mils in order to make our solution. So again we're going to set up a little ratio and the proportion equation over here. So we know that our molecular weight tells us that 58.44 grams of sodium chloride make up one mole of sodium chloride. So therefore how many grams will make up 0.5 moles of sodium chloride. So we cross multiply again which in this case is 58.44 grams of sodium chloride but I don't have to write sodium chloride here again. Times 0.5 moles divided by one mole. So our mole will cancel out and we're going to multiply 58.44 by 0.5. So that will give us 29.22 grams. So in order to make up the solution we're going to dissolve 29.22 grams of sodium chloride and bring the volume and we're going to bring the volume to 250 mils.