c. Using your values from a&b, calculate the molarity of the saline solution

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1 HMSA Chemistry Ms. Ye Name Date Block I.V. fluids and Molarity 1. Normal saline solutions used for I.V. drips contain 0.9 grams of NaCl per 100 ml of solution. a. Convert the grams of Nacl in the saline solution to moles of NaCl b. Convert the milliliters of saline solution into liters of solution. c. Using your values from a&b, calculate the molarity of the saline solution d. Using the Molarity you calculated from c, calculate the number of moles of NaCl you would need to make 1000 ml of saline solution. e. Using your answer from d, how many grams of NaCl would you need to make 1000 ml of the saline solution? f. Why do you think an I.V. drip is made up of a solution of 0.9 grams of NaCl/100 ml of solution? Why can t we hook a patient up to an I.V. of pure water?

2 2. When diabetic patients experience low blood sugar, a dextrose solution (D5W) may be administered. Dextrose is a form of glucose (C6H12O6) and is utilized by the body cells for basic metabolic needs (cell respiration). The dextrose solution contains 5 grams of dextrose per 100 ml of solution a. Calculate the molarity of the dextrose solution (you ll need to convert both grams & ml) b. How many grams of dextrose would you need to make a 2500 ml dextrose solution of the same concentration as the one in part a?

3 Dilutions Activity Assume your beaker contains a 3.0 M solution (your stock solution ) 1. Based on the given molarity above and the volume (estimate from the beaker) of the solution, how many moles of solute are in your solution? Show work. 2. Pour ~50 ml of your stock solution into a separate container. Does this 50 ml solution have the same molarity as the stock solution? If not, how would the molarity be different? 3. Add ~50 ml of water to your 50 ml solution (from #2). Does this new ~100 ml solution have the same molarity as your stock solution? If not, how would the molarity be different? 4. What you just did in step 3 is known as a dilution. Explain what you think it means to dilute a solution

4 Use the Model below to set up your dilution Making Dilutions: M = Molarity of Solution V = volume of solution = *since volume (V) is on both sides of the equation, you need to make sure they are both in the same units! They can both be in L or both in ml just as long as V1 and V2 are in the same unit! Sample Problem: What volume of concentrated (12 M) HCl is needed to make 500 ml of 2 M HCl? = (12 ) = (2 ) (500 ) =. This means that you need to pour 83.3 ml of the concentrated 12 M solution into a separate container, then add enough water so you have 500 ml of solution. This is how you would dilute your solution to a concentration of 2 M. Consider your stock solution from the first part of your lab (concentration of 3.0 M). You need to take your stock solution and dilute it to make ml of a 1.2 M solution. 1. Using the dilution formula above, calculate the volume of your stock solution that you would need to make the diluted solution. 2. Measure out the volume of stock solution needed to make your diluted solution and pour it into the ml volumetric flask. 3. Do you have 50 ml of solution? About how much more water do you need to add to make a 50 ml solution?

5 DILUTIONS PRACTICE PROBLEMS M = Molarity of Solution V = volume of solution = *since volume (V) is on both sides of the equation, you need to make sure they are both in the same units! They can both be in L or both in ml just as long as V1 and V2 are in the same unit! 1. What volume of concentrated hydrochloric acid (12.0 M) is needed to make 3.0 L of 1.0 M HCl? 2. What volume of concentrated ammonium hydroxide (14.5 M) is needed to make 250 ml of 0.5 M NH4OH? 3. If I have 340 ml of a 0.50 M NaBr solution, what will the concentration be if I made a new solution with the total volume is 560 ml? 4. If I dilute 250 ml of 0.10 M lithium acetate solution to a volume of 750 ml, what will the concentration of this solution be? 5. Using 52.5mL, a M solution was diluted to ml. What is the new concentration of this solution? 6. A stock solution of 10.0 M NaOH is prepared. From this solution, you need to make ml of M solution. How many ml will be required?

6 Homework: Molarity Practice (Molarity = moles of solute/liters of solution) Assume you placed a sample of a potato in 3 different solutions. Assume your potato sample has 1.3 grams of NaCl and the liquid volume of your potato is 350 ml. 1. Calculate the molarity of NaCl in the potato. 2. Calculate the molarity of the following salt solutions: a. 0.1 grams of NaCl in 100 ml of solution b grams of NaCl in 100 ml of solution c. 2 grams of NaCl in 100 ml of solution 3. Compare the molarities of the salt solutions to the molarity of the NaCl in the potato. If you placed a potato in all 3 solutions, which solution will be a. Hypertonic relative to the potato? How will the size of the potato change? b. Hypotonic? How will the size of the potato change? c. Isotonic? How will the size of the potato change?

7 Dilutions Practice (M1V1=M2V2) 4. A stock solution of 1.00 M NaCl is available. How many milliliters are needed to make ml of M solution? 5. What volume of M KCl is needed to make ml of M solution? 6. Concentrated H2SO4 is 18.0 M. What volume is needed to make 2.00 L of 1.00 M solution? 7. Concentrated HCl is 12.0 M. What volume is needed to make 500. ml of 1.50 M solution? L of M NaNO3 must be prepared from a solution known to be 1.50 M in concentration. How many ml of stock solution are required?