PRE LABORATORY EXERCICES: Show all your calculations! 1. 3. Calculate the mass of potassium dichromate, KCrOy, required to prepare 100 cm of a 2.00x 10 mol dm solution. (Use = 204.2g mol as the molar mass of KCrO7) (2 marks) Calculate the mass of potassium permanganate, KMnO4, required to prepare 1 dm of a 5.00 x 10 mol dm solution. (Use 158.04g mol' as the molar mass of KMnO4) (2 marks) Given that KMnO, has an absorptivity of 2.41 x 104 dm mol at 545 nm, calculate the expected absorbance at 545 nm at a 0.00250 mol dm solution of KMnO, using a cell width of 1.0cm. (2 marks) Read Appendix 6. TOTAL = 6 marks