Chemistry HS/Science Unit: 10 Lesson: 02 Making a 1.0 Molar Solution KEY Solutions are used in many everyday products. The preparation of a solution requires use of a periodic table and careful laboratory procedures. Make your calculations using dimensional analysis and significant figures. Molarity (M) is defined as the number of moles of solute divided by the number of LITERS of solution. Molarity = Moles of solute Liters of solution FOR EXAMPLE: 1.0 mole of sodium chloride, added to enough water to make 1.0 liter of solution, produces a 1.0 M solution of sodium chloride. Procedures for the preparation of 1.00 L of a 1.0 M solution of sodium chloride: 1. Calculate the molar mass of sodium chloride, NaCl: 58.44 g/mol. 2. How do you obtain one mole of sodium chloride? Mass it on an electronic balance to the nearest 0.1 g. (*Note: Since 1.0 M is 2 significant figures, massing on a balance to the the nearest 1.0 g would be sufficient.) 3. How much water do you add to make a liter of solution? You add enough to come up to the line on a 1.00 L volumetric flask 4. Why would using a pipette be useful when making this solution? To add small amounts of water 5. Tell your teacher that your group is ready to make your solution. Be prepared to explain your process to make this 1.0 M solution. ________ Teacher approval 6. Place 58.4 grams of sodium chloride in a 1.00 L volumetric flask. Fill the volumetric flask with a little less than 1.00 liter of water, and swirl the flask to dissolve the NaCl. When all of the sodium chloride has dissolved, carefully fill the flask to the 1.00 L mark using a pipette if needed. Swirl one more time. 7. Clean up your lab table. Pour your sodium chloride solution into a container as directed by your teacher. 8. Return to your seat, and write the procedure for making 1.00 L of a 1.00 M solution of sodium carbonate in your science notebooks. The molar mass of sodium carbonate is 105.988 g/mol or 106.0 to 4 significant figures. Place 106.0 grams of sodium carbonate, Na2CO3, in a 1.00 L volumetric flask. Fill the volumetric flask with a little less than 1.00 liter of water, and swirl the flask to dissolve the ©2012, TESCCC 05/22/13 page 1 of 1 Chemistry HS/Science Unit: 10 Lesson: 02 Na2CO3. When all of the sodium carbonate has dissolved, carefully fill the flask to the 1.00 L mark using a pipette if needed. Swirl the flask one more time. 9. Lastly, summarize the procedure for making 500 mL of a 1.00 M solution of sodium carbonate in your science notebooks. The molar mass of sodium carbonate is 106.0 g/mol, so for 500 mL of a 1.00 M sodium carbonate solution, you would need: 106.0 g/mol x 500 mL x (1 L / 1000 mL) x (1.00 mol/L) = 53.0 g Place 53.0 grams of sodium carbonate in a 500 mL volumetric flask. Fill the volumetric flask with a little less than 500 mL liter of water, and swirl the flask to dissolve the Na2CO3. When all of the sodium carbonate has dissolved, carefully fill the flask to the 500 mL mark using a pipette if needed. Swirl the flask one more time. ©2012, TESCCC 05/22/13 page 2 of 1.