Catalyst – September (20-3), 2009Please 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), 2009

1. 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 scales4. Plot each point5. 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 cm3)

∆y/ ∆x

Slope of a Mass vs. Volume graph = Density!!!!

How to Calculate Slope (m)

1. Pick 2 points(x1, y1)

(x2, y2)

2. Plug values into equation:m = (y2 – y1)/(x2 – x1)

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)

1.0 3

3.0 8.5

5.0 13.8

7.0 19.2

9.0 24.5

Calculate Density Using a Graph’s Slope

Mass vs. Volume: Mystery Substance

0102030405060708090100

0 10 20 30 40 50

Volume (mL)

Mas

s (g

)

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 g180 mg

How can we

compare these units?

DIMENSIONAL

ANALYSIS

Back to Coke!

DensityClassic > DensityDiet

VolumeClassic = 355 mL VolumeDiet = 355 mL

MassClassic = liquid + 39 g MassDiet = liquid + 0.18 g

What about other kinds of Coke?

39 g sugar

0.18 g

NutraSweet

39 g sugar

42 g sugar

0.01 - 0.085 g

Nutra Sweet and acesulfame

potassium (ace-k)

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 couldyou

separatethem?

Just addwater!

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 waterEx: 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.