CONCENTRATIONInvestigation 1Soft 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 more solute 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

CONCENTRATIONInvestigation 2Salt 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.