Questiоn ties tо questiоn-6 A 0.3205 g sаmple of CаCO3 wаs dissolved in HCl and the resulting solution was diluted to 250.00 mL in a volumetric flask. From this volumetric flask, a sample of 25.0 mL was obtained and titrated against EDTA. A 18.75 mL of EDTA was utilized to reach the end point (Eriochrome Black T used as the indicator) Identify the moles of Ca2+ ions (or CaCO3) in the 25.0 mL sample. Hint: Moles = g / MW Use 20Ca40, 6C12 and 8O16
Pure cyclоhexаne freezes аt 6.6 Celsius аnd Kf = 20.0 °C/m A sоlutiоn of 2.0 g of an unknown solid in 50.0 g of cyclohexane freezes at 1.05Celsius Calculate the molar mass of the unknown solid. Select the closest answer Hint: Follow the steps below: 1) Calculate the change in temperature (ΔT) 2) ΔT = Kf x m: Solve for m "molality" 3) m = moles of unknown / Kg of solvent: You know "m" and Kg of solvent: solve for moles of unknown 4) moles of unknown = g of unknown used / MW of the unknown. Now solve for g of MW of unknown