First Sem AY 2018-2019 PS 2 with ans.pdf

A rank nutrients a to g in decreasing polarity 2

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chromatogram is shown in the figure. A. Rank nutrients A to G in decreasing polarity. ( 2 points ) B. Whose medicine has more nutrients? ( 1 point ) C. Calculate the retention factors of the nutrients present in the medicine with more nutrients. ( 10 points ) 3. An impure Mg sample weighing 0.0320 g was inserted into an inverted eudiometer containing excess HCl. Upon reaction, H 2 gas was produced above the liquid column. A. Write the balanced chemical equation of the reaction that has occurred. ( 1 point ) B. If the height difference between the liquid column in the eudiometer and the water level outside the eudiometer is 15.5 cm (refer to the diagram), calculate the pressure of the trapped air above the liquid column in mmHg. Assume that the atmospheric pressure is 1.01325 bar. ( 2 points ) C. Calculate the pressure exerted by H 2 in Torr given that the vapor pressure of water at the experiment’s condition (T = 31.0°C) is 33.7 Torr. ( 1 point ) D. If 32.8 mL of trapped air was measured, how much H 2 gas (in moles) was produced? Note that the experiment was performed at T = 31.0°C. ( 3 points ) E. Calculate the mass (in grams) of Mg that has reacted. ( 2 points ) F. What is the percent purity of the sample? ( 1 point )
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Institute of Chemistry University of the Philippines Diliman Chemistry 16.1 LAB PROBLEM SET 2 FIRST SEMESTER, A.Y. 2018-2019 Chem 16.1 First Semester 2018-2019 PS2 Page 5 of 5 4. A solution was prepared by dissolving 2.50 g of MgCl 2 (MM of 95.21 g/mol) in 150.00 g of solvent X. It was determined that the boiling point of this solution was 0.50°C higher than the normal boiling point of the pure solvent X. A. Assuming that the solution is ideally dilute, what is the van’t Hoff factor ? ( 1 point ) B. What is the molal concentration of the solute in the solution? ( 2 points ) C. What is the K b of solvent X? ( 3 points ) D. What is the freezing point of the solution if the freezing point of pure solvent is -4.53°C and K f = 3.25°C/m? ( 3 points )
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