LQB180: Biomolecules & Life Processes- Chemistry Report Writing Assignment

Internal Code: TV181

Chemistry Report Writing Assignment:

Task: Question 1 a) Write the chemical formula and the molar mass (g/mol) for the amino acid selenocysteine. b) Complete the table by writing the relative masses (g) and %’s of the elements found in 1 mole of selenocysteine. c) Stachyose is a tetrasaccharide found in vegetables and many plants. You are provided with a 0.8 M solution of stachyose. Molar mass: stachyose (C24H42O21) = 666.58 g/mol. What volume (in mL) will contain 350 ?moles of stachyose? Question 2 a) Calculate the concentration of hydrogen ions [H+] for 1. Lemon juice, pH 2.1 2. Icelandic Glacial brand water, pH 8.4 3. Milk, pH 6.5 b) Calculate the pH of [3 marks] 1. 85 mM NaOH 2. Milk of Magnesia, [H+] = 3.20 x 10-11 M 3. 2.2 M Hydrobromic acid (HBr) c) Calculate the pH obtained by dissolving 3.68 g of anhydrous potassium ethanoate (MW = 98.14 g/mol) in 100 mL of 0.25 M ethanoic acid, given that the pKa of ethanoic acid = 4.75. Question 3 You need to prepare 100 mL of a 0.5 M solution of LiCl. You have 50 mL of a 0.65 M LiCl solution and 20 mL of a 5% (w/v) LiCl solution. 1. Molar mass of LiCl = 42.39 g/mol 2. % (weight / volume) means mass (in g) in volume (100 mL) What volume of 5% LiCl and water needs to be added to the 50 mL of 0.65 M LiCl solution to make up 100 mL of 0.5 M LiCl? Question 4 Midori Melon Liqueur contains 20 % (v/v) ethanol, Wolf Blass Platinum Label Shiraz contains 14 % (v/v) ethanol and Old Speckled Hen Ale contains 5 % (v/v) ethanol. 1. Absolute (100% vol/vol) ethanol: density = 0.79 g/mL 0 %’s are vol/vol ? i.e., volume of EtOH in 100 mL total volume 2. Molecular weight of ethanol = 46.1 g/mol a) Calculate the molarity of absolute ethanol (100% vol/vol). [2 marks] b) Calculate the concentration of ethanol in the 3 separate beverages. 1.. Give the concentrations in g/L 2.. Give the concentrations as molarities [3 marks] c) Determine the mass (g) of ethanol in each of the following 3 beverages. [3 marks] 1. 500 mL bottle of Midori Melon Liqueur 2. 750 mL bottle of Wolf Blass Platinum Label Shiraz 3. 6 pack (6 x 355 mL bottles) of Old Speckled Hen Ale Which beverage contains the highest amount (in g) of ethanol?