making solutions , dilutions and use of the spectrophotometer LAB 2: DATA SHEET
ID: 52304 • Letter: M
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making solutions , dilutions and use of the spectrophotometer LAB 2: DATA SHEET PREPARING SOLUTIONS, MAKING DILUTIONS, AND USE OF THE SPECTROPHOTOMETER Name: Group #: Project 1: Making Molar Solutions In this project you will use calculations, conversions, and dilutions to make a 1.6 x 10'M solution. 1. Make a 0.4 M sodium chloride (NaCl, FW = 5844) stock solution by dissolving an appropriate Lab Section: Members: amount of NaCl in a 100-mL volumetric flask about half filled with water (H,O). 0.4 M NaCl = 0.4 moles Nad/liter of solution. Therefore 0.4 moles/L x 5844 g/mole = g/L g NaCl If g NaCl is used to make 1 liter of solution, will be used to make 100 mL of solution. After the NaCl is completely dissolved, add enough H,O to fill the flask to the 100-mL. calibration mark. Cap the lask and invert it several times to insure complete mixing and a uniform solution. Label this solution as 0.4 M NaCl stock. 2. Dilute the 0.4 M NaCl solutionby adding 1 mL of the 0.4 M solution to 9 mL of water in a 10 test tube. Label the test tube as 0.04 M. Seal with a piece of parafilm and invert the test tube several times to mix the contents dilution of 0.4 M Nad--x 0.4 M = 0.04 M NaCl = 10 g/mL 10 Dilute the 0.04 M NaCI solution by placing 2 mL, of the 0.04 M NaCl solution into a 100-mI. beaker and use a 50-ml, graduated cylinder to add 48 mL of H,O to the beaker. Add a parafilm seal and swirl the beaker to mix the contents. Label the beaker 1.6 x 10'M. Record the NaCl concentration in /mL (with 2 significant figures) below. 3. 25 25 dilution of0.04 M Naa-25x0.0415x10"MNaa dilution of 0.04 M Naci = 1 x 004 M = 1.6 × 10, M NaC1 ug/mL BIOL 299 Fall 2015 Lab 2: Solutions and Dilutions- Page 31Explanation / Answer
1) 0.4M NaCl = 0.4 moles NaCl/litre of solution, Therefore
0.4 moles/L x 58.44g/mol = 23.37 g/L
If 23.37 g NaCl is used to make 1 litre of solution, 2.33 g NaCl will be used to make 100 mL of solution.
2) 0.04 M NaCl = 233000 ug/mL
3) 1/25 x 0.04 M = 1.6 x 10-3 M NaCl = 9320 ug/mL
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