Slide 1Slide 2Slide 3A solution of 5.00 g of an unknown substance in 0.100 kg of benzene freezes at 4.1°C ( Tf ). What is the molar mass of the unknown substance? Kf (benzene) = 5.12°C/m; Tf ◦ (benzene) = 5.50°C. Use ΔTf = m∙Kf to calculate mUse m = moles/ kg solventto calculate molesStep 2Step 3Step43Divide mass (g) of unknown with moles to get molar mass of unknownStep 1 Use Tf = Tf◦ - ΔTf to calculate ΔTf183.15 g/molCalculate the osmotic pressure of the solution containing 1.5g of ethylene glycol (C2H6O2) in 50ml of solution at 25◦CUse Π = MRT(T in kelvin)Step 2Step 1Use M = moles / L To calculate molarity MConvert mass (g) to molesStep 3Π =11.81A solution containing 27.55 mg of an unknown protein per 25ml solution has an osmotic pressure of 3.22 torr at 25◦C. What is the molar mass of the protein6.36 X 103
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