Acetonitrile ( C H 3 C N ) is a polar organic solvent that dissolves a wide rang

Question

Acetonitrile (CH3CN) is a polar organic solvent that dissolves a wide range of solutes, including many salts. The density of a 1.70M LiBr solution in acetonitrile is 0.826g/cm3 . Part A Calculate the concentration of the solution in molality. mol/kg SubmitMy AnswersGive Up Part B Calculate the concentration of the solution in mole fraction of LiBr. SubmitMy AnswersGive Up Incorrect; Try Again; 3 attempts remaining Part C Calculate the concentration of the solution in mass percentage of CH3CN. % SubmitMy AnswersGive Up Provide FeedbackContinue Incorrect. Incorrect; Try Again; 3 attempts remaining. No additional feedback.
Acetonitrile (CH3CN) is a polar organic solvent that dissolves a wide range of solutes, including many salts. The density of a 1.70M LiBr solution in acetonitrile is 0.826g/cm3 . Part A Calculate the concentration of the solution in molality. mol/kg SubmitMy AnswersGive Up Part B Calculate the concentration of the solution in mole fraction of LiBr. SubmitMy AnswersGive Up Incorrect; Try Again; 3 attempts remaining Part C Calculate the concentration of the solution in mass percentage of CH3CN. % SubmitMy AnswersGive Up Provide FeedbackContinue Incorrect. Incorrect; Try Again; 3 attempts remaining. No additional feedback. Acetonitrile (CH3CN) is a polar organic solvent that dissolves a wide range of solutes, including many salts. The density of a 1.70M LiBr solution in acetonitrile is 0.826g/cm3 . Acetonitrile (CH3CN) is a polar organic solvent that dissolves a wide range of solutes, including many salts. The density of a 1.70M LiBr solution in acetonitrile is 0.826g/cm3 . Acetonitrile (CH3CN) is a polar organic solvent that dissolves a wide range of solutes, including many salts. The density of a 1.70M LiBr solution in acetonitrile is 0.826g/cm3 . Acetonitrile (CH3CN) is a polar organic solvent that dissolves a wide range of solutes, including many salts. The density of a 1.70M LiBr solution in acetonitrile is 0.826g/cm3 . Part A Calculate the concentration of the solution in molality. mol/kg SubmitMy AnswersGive Up Part B Calculate the concentration of the solution in mole fraction of LiBr. SubmitMy AnswersGive Up Incorrect; Try Again; 3 attempts remaining Part C Calculate the concentration of the solution in mass percentage of CH3CN. % SubmitMy AnswersGive Up Provide FeedbackContinue Part A Calculate the concentration of the solution in molality. mol/kg SubmitMy AnswersGive Up Part B Calculate the concentration of the solution in mole fraction of LiBr. SubmitMy AnswersGive Up Incorrect; Try Again; 3 attempts remaining Part C Calculate the concentration of the solution in mass percentage of CH3CN. % SubmitMy AnswersGive Up Part A Calculate the concentration of the solution in molality. mol/kg SubmitMy AnswersGive Up Part B Calculate the concentration of the solution in mole fraction of LiBr. SubmitMy AnswersGive Up Incorrect; Try Again; 3 attempts remaining Part C Calculate the concentration of the solution in mass percentage of CH3CN. % SubmitMy AnswersGive Up Part A Calculate the concentration of the solution in molality. mol/kg SubmitMy AnswersGive Up Part B Calculate the concentration of the solution in mole fraction of LiBr. SubmitMy AnswersGive Up Incorrect; Try Again; 3 attempts remaining Part C Calculate the concentration of the solution in mass percentage of CH3CN. % SubmitMy AnswersGive Up Part A Calculate the concentration of the solution in molality. mol/kg SubmitMy AnswersGive Up Part A Calculate the concentration of the solution in molality. mol/kg SubmitMy AnswersGive Up mol/kg mol/kg SubmitMy AnswersGive Up Part B Calculate the concentration of the solution in mole fraction of LiBr. SubmitMy AnswersGive Up Incorrect; Try Again; 3 attempts remaining Part B Calculate the concentration of the solution in mole fraction of LiBr. SubmitMy AnswersGive Up Incorrect; Try Again; 3 attempts remaining SubmitMy AnswersGive Up Incorrect; Try Again; 3 attempts remaining Incorrect; Try Again; 3 attempts remaining Incorrect; Try Again; 3 attempts remaining Part C Calculate the concentration of the solution in mass percentage of CH3CN. % SubmitMy AnswersGive Up Part C Calculate the concentration of the solution in mass percentage of CH3CN. % SubmitMy AnswersGive Up % % SubmitMy AnswersGive Up Provide FeedbackContinue Incorrect. Incorrect; Try Again; 3 attempts remaining. No additional feedback.


Acetonitrile (CH3CN) is a polar organic solvent that dissolves a wide range of solutes, including many salts. The density of a 1.70M LiBr solution in acetonitrile is 0.826g/cm3 . Part A Calculate the concentration of the solution in molality. mol/kg SubmitMy AnswersGive Up Part B Calculate the concentration of the solution in mole fraction of LiBr. SubmitMy AnswersGive Up Incorrect; Try Again; 3 attempts remaining Part C Calculate the concentration of the solution in mass percentage of CH3CN. % SubmitMy AnswersGive Up Provide FeedbackContinue Calculate the concentration of the solution in molality. Calculate the concentration of the solution in mole fraction of LiBr. Calculate the concentration of the solution in mass percentage of CH3CN.

Explanation / Answer

(A) Consider 1 L = 1000 cm3 of solution

Moles of LiBr = volume x molarity = 1 x 1.70 = 1.70 mol


Mass of LiBr = moles x molar mass of LiBr

= 1.70 x 86.845 = 147.64 g


Mass of solution = volume x density = 1000 x 0.826 = 826 g


Mass of acetonitrile = mass of solution - mass of LiBr

= 826 - 147.63 = 678.36 g = 0.67836 kg


Molality = moles of LiBr/mass of acetonitrile

= 1.70/0.67836 = 2.51 mol/kg


(B) Moles of acetonitrile = mass/molar mass of acetonitrile

= 678.36/41.052 = 16.524 mol


Mole fraction of LiBr = moles of LiBr/(moles of LiBr + moles of acetonitrile)

= 1.70/(1.70 + 16.524) = 0.0933


(C) Mass percent of acetonitrile = mass of acetonitrile/mass of solution x 100%

= 678.36/826 x 100% = 82.1%

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