Concentration Investigation 1 Soft Drink Recipes
LEQ: What Happens to a soft-drink solution when you increase the amount of powder in a given amount of water?
Let’s Review • Mixtures and Solutions Review
2 solutions • 1A • 2B
PARTY TIME!!!!!!!!!!!! • The problem is…………………I lost the label. I can’t remember how much solute (Kool-Aid) to add to the solvent (water). • Our challenge is to find out how much I should add to 1000 of water to make it taste good. • As I mix it up, I need you to observe • On your recipe sheet, record your observations by making both “visual” and “taste” observations. • Review: Is the drink a mixture? Is it a solution? How can we test it to determine if it is a solution? How can we determine if we have a saturated solution?
Directions • Each of you will get a small sample of each of two different solutions to observe and taste. 1A and 2B • Tasting is to be done last, after all of the other observations are completed. • Describe how each solution is both similar and different. ( 1A and 2B) • Create a VENN DIAGRAM to demonstrate their similarities and differences.
Observations • Which drink tasted sweeter? • When a soft drink solution tastes sweet ( and looks dark) it is a concentrated solution. • When it tastes weak and looks light, it is a dilute solution. To dilute a solution, is to add more liquid to it, so it become less concentrated.
What is concentration? • The amount of material dissolved in a volume of a liquid. Volume is (the 3-D space occupied by a liquid). • The more material dissolved in a given amount of liquid, the more concentrated the solution. In other words, the moresolute added to a given amount of solvent, the higher the concentration.
On a note card:Explain What Happens to a soft-drink solution when you increase the amount of powder in a given amount of water
Concentration Investigation 2 Salt Concentrations
LEQ: How can you determine which of two salt solutions is more concentrated?
Review How do you make a concentrated soft- drink solution? How can you tell which of two soft-drink solutions is more concentrated?
Salt solutions • Today we are going to investigate the concentrations of salt solutions, but there is one problem: we are not permitted to taste the salt solutions, and they are colorless. • Discuss in your groups how you can determine which salt solution is more concentrated?
Salt Solutions 1 and 2 • Turn to the sheet, Salt Concentration. Preview the first part of the sheet. • Each group will get 2 plastic cups and label each: Solution 1 and Solution 2. • Follow the directions in part 1 of the sheet. • Solution 1: 1 spoon of salt an 50 ml of water. • Solution 2: 3 spoons of salt and 50 ml of water.
Use balance to compare solutions • When using a balance to compare concentrations of solutions, you must compare equal volumes. • Using a syringe, draw up 50 ml of the solution. Make sure there are no air bubbles. If there are air bubbles, place the solution back into the cup and try again. • Pour out any left over liquid, and transfer the liquid from the syringe back into the cup. • Balance the scale with an empty cup on both sides of the scale. • Put 50 ml of PLAIN water into a labeled cup. • weigh and record: solution 1 against the plain water solution 2 against the plain water.
Conclusions • When you compare equal volumes of two solutions on a balance, and one is heavier than the other, the heavier one is more concentrated. • Why must the volumes be equal? (Turn and discuss)
Make SOLUTION 3 • Read part 3 of the student sheet and prepare solution 3 in a labeled cup • ( Three spoonfuls of salt and 150 ml of water) • Compare solution 3 to solution 2 • Which solution is most concentrated? • Now compare solutions 1 and 3. Which is more concentrated?
RESULTS • Solution 2 is more concentrated than solution 3 • Solutions 1 and 3 have equal concentrations
Ticket out • Write a $2 summary explaining how you were able to determine which of two salt solutions was more concentrated.
Investigation 3 Mystery Solutions
LEQ: How can you determine if three solutions have different concentrations? • Observe the three solutions. • Develop a plan to determine which solution, if any, has the highest concentration. • You must put your plan in writing and be sure to list all steps, as you will follow this plan. • Your plan should be written so anyone can follow it. • You will need 3 cups, 3 labels, a syringe and 50 ml of each solution in each of the three cups.