Catalyst – September (20-3), 2009 Please place HW on your desk! 1. What is the slope of a line? (Think about what you learned in Algebra!) 2. If Huda puts another box onto her boat, then it will sink. Identify the independent variable, dependent variable, and control group in this situation.

Catalyst – September (20-3), How do you calculate slope from a mass vs. volume plot? 2. If Huda puts another box onto her boat, then it will sink. Identify the independent variable, dependent variable, and control group in this situation.

Today’s Agenda  Catalyst  Density of Water Lab  Coke/Diet Coke Demo!  Separating Mixtures + Student Demos  Whiteboards?  Exit Question

Today’s Objectives  SWBAT calculate the density of water by making a density graph.  SWBAT plan procedures to separate mixtures based on physical properties.

Density of Water Lab  In lab, each group will measure the mass of 2 different volumes of water  Each group will record their data on the board  Each student will copy data and complete lab report in class  You have 30 minutes to FINISH the lab

How to Graph Density 1. Label axes (x = volume, y = mass) 2. Title graph (y-axis vs. x-axis) 3. Determine scales 4. Plot each point 5. Draw trend line (line of best fit) For density graphs, the slope equals the density!

Slope and Density  What is the equation for density?  What is on the y-axis?  What is on the x-axis?  What does slope represent? Mass (g) Volume (mL or cm 3 ) ∆y/ ∆x Slope of a Mass vs. Volume graph = Density!!!!

How to Calculate Slope (m) 1. Pick 2 points (x 1, y 1 ) (x 2, y 2 ) 2. Plug values into equation: m = (y 2 – y 1 )/(x 2 – x 1 )

Calculating Density Using Slope  Use the information in the following chart to determine which substance was involved in the experiment?  Substance Density  Copper: 8.96 g/mL  Aluminum: 2.70 g/mL  Zinc: 7.13 g/mL Volume (mL)Mass (g)

Calculate Density Using a Graph’s Slope

Class Work Time  Complete NUMBER TWO of your worksheet  Calculate densities using your graphs!

It’s Demo Time!  Materials  1 can Coke  1 can Diet Coke  Tub of water  Nutritional information  Example samples

Why did that happen?  ___________ sugar in Coca-Cola Classic  ___________ NutraSweet in Diet Coke 39 g 180 mg How can we compare these units? DIMENSIONALANALYSIS

Back to Coke! Density Classic > Density Diet Volume Classic = 355 mL Volume Diet = 355 mL Mass Classic = liquid + 39 gMass Diet = liquid g

What about other kinds of Coke? 39 g sugar 0.18 g NutraSweet 39 g sugar 42 g sugar g Nutra Sweet and acesulfame potassium (ace-k) Nutritional Info Nutritional Info

So what if….  What if you had a GIGANTIC swimming pool full of Coke Classic cans and Diet Coke cans?  How could you separate them?

Solution! How could you separate them? Just add water!

Separating Mixtures  Key Point #1: Mixtures are physically combined, so they can be PHYSICALLY separated.

Real-Life Examples of Separating Mixtures  Separating components of blood  Separating oil from water in an oil spill  Getting drinkable water in third world countries

How you do that?  Key Point #2: Chemists separate mixtures by using differences in physical properties of each part.  Physical Properties:  Density  Solubility  Magnetism  Boiling Point

Density  Based off differences in density, you can separate liquids from each other Ex: Oil and Water

Magnetism  Based on differences is magnetism, you can separate magnetic objects from non- magnetic objects Ex: Rocks and Coins

Filtration  Based on differences in phase state, you can separate solids from liquids using filtration Ex: Sand and water Ex: Spaghetti and water

Crystallization  Based on differences in boiling points, you can separate dissolved solids from liquids  Ex: Boil salt water to crystallize salt and evaporate water

Distillation  Based on differences in boiling points, you can separate two liquids from each other.  Liquid A has a boiling point of 100°C  Liquid B has a boiling point of 110°C  How could I separate these two mixtures?

Whiteboards Identify the technique (filtration, distillation, or crystallization) you would use to separate the following mixtures: (1) Remove rocks from an ocean water sample. (2) A solution of salt water. (3) A mixture of oil and water. (4) Isolate sugar from a sugar-water solution. (5) Salt and ammonium chloride mixture (salt is not soluble in ammonium chloride). (6) A mixture of paperclips and rice. (7) A mixture of water and oil.

Exit Question  Give a possible value of the density of diet coke and coke.