I need some help in chem and if someoen could please help me out.. would be soo great?

NetherCraft 0

A solution was prepared by dissolving 29.0 g of KCl in 225 g of water.

A)Calculate the mass percent of in the solution.

B) Calculate the mole fraction of in the solution.

C)Calculate the molarity of KCl in the solution if the total volume of the solution is 239 mL and what is teh molality of KCl

3 Answers

  • b) 225 g water

    mol = 225g / 18.016g/mol = 12.5 mol water

    29.0 g KCl

    mol = 29.0 / 74.55g/mol = 0.389 mol KCl

    Therefore mole fraction KCl = 0.389 / (.389 + 12.5) = 0.030

    c) from above, mol KCl is 0.389, vol = 0.239L

    Molarity = 0.389mol / 0.239L = 1.63 mol/L

  • Mass percent and mole fraction work pretty much the same way – they are both percentages. Any percent is sample / total x 100.

    A) is straight forward. B) Convert both to moles and the sample / total.

    C) If the solvent is water, then molarity and molality are the same thing as the density of water 1g/ml – Liters = Kilograms.

    Convert the KCl to mole and then divide by lters.

  • I can only answer A. Divide KCl with H20. So 29g/225g = 0.13 times 100. It’s about 13% mass in the solution.

Leave a Reply

Your email address will not be published. Required fields are marked *