Acetonitrile (CH₃CN) is a polar organic solvent that dissolves a wide range of solutes, including many salts. The density of a 1.80 M LiBr solution in acetonitrile is 0.826 g/cm³. Calculate the concentration of the solution in (b) mole fraction of LiBr,

Video transcript

Hi everyone here we have a question telling us that acetone is a highly effective solvent that can dissolve both organic and inorganic compounds and some salts to a 2. moller lithium chloride solution in acetone has a density of 0.8529 g per centimeters cubed. What is the mole fraction of lithium chloride in the solution? So our polarity is going to equal most divided by leaders. So to .40 Polarity equals 2.40 moles of lithium chloride In one L of solution. So our models of lithium chloride is 2.40 are mass of our solution equals the mass of lithium chloride plus the mass of acetone. The molar mass of lithium chloride equals 6.941 g per mole plus 35.45 g per mole Equals 42. g per mole. Our mass of a lithium chloride Equals 2.40 moles Times 42. g Permal. And our moles cancel out here. And that equals .7384 g 0. g per cm cubed equals 0.85 to nine g per milliliter. The mass of our solution Equals one L of solution, Times one mil liter, Divided by 10 to the -3. Leaders times 0.85 to nine g per milliliter. And our leaders are canceling out and our middle leaders are canceling out and that gives us 852.9 g. Our mass of acetone Equals 852.9 g -101. g equals 751. g of acetone. Our molar mass of acetone Equals 12. g per mole Times three for carbon Plus 1.008 g per mole Times six for hydrogen plus 16 g per mole equals 58.78 g per mole. Our moles of acetone Equals 751.1616 grams of acetone times one mole of acetone Divided by its molar mass. So 58.078 g of acetone. So our g are canceling out here and that equals 12.9337 moles. So our mole fraction equals moles of lithium chloride, divided by moles of lithium chloride plus moles of acetone. So our mole fraction equals 2. zero moles Divided by 2.40 moles plus .9337 moles. And our mole fraction equals 0.157. And that is our final answer. Thank you for watching. Bye