GRAPHING AND VARIABLES

```GRAPHING AND VARIABLES
X axis—holds the independent
(manipulated) variable
Y axis—holds the dependent (responding)
variable
***DRY MIX***
ACTIVATOR:
WORD SPLASH--MEASUREMENT

List as many terms or phrases that we’ve
discussed in unit 2 that deal with
measurement
DATA TABLES AND VARIABLES
X (INDEPENDENT)
Y (DEPENDENT)
Ex: Volume (mL)
Ex: Mass (grams)
2.0
7.9
3.0
16.2
4.0
25.0
5.0
32.3
SLOPE
Is determined by the first and last data
points
 Last y – first y =
y2 - y1
last x – first x
x2 - x1
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Ex: 32.3 – 7.9
5.0 – 2.0
= 24.4 = 8.1
3.0
DIRECT VS. INDIRECT
PROPORTIONS
DIRECT
INDIRECT (aka
INVERSE)
Shows a negative slope
Factors do opposite things
Shows a positive slope
both factors increase or
both factors decrease (do
the same thing)
Ex: speed = distance/time
Ex: area = length x width
density = mass/ volume
Graph:
Graph:
FLIPPED ASSIGNMENT--DENSITY
Visit the following website:
http://mswipc.com/problem_sets/density/de
nsity_sample_problems.htm

Review all 3 types of density problems
tomorrow.
ACTIVATOR: Explain why these
substances are layered?
DENSITY DEMONSTRATIONS:
(TEACHERTUBE.COM)
 1. The density of liquids
 2. Underwater volcano
 3. The density of water is 1
 4. Dr. Reich’s density lab
http://www.teachertube.com/viewVideo.ph
p?video_id=7593
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FOR DENSITY LAB:
 ---DO NOT MOVE CHAIRS AROUND
 ---MUST KEEP GOGGLES ON AT ALL TIMES at
station 2!!!
CLEAN UP
 ---WHEN USING SOAP TO WASH CYLINDER,
ONLY USE 1 DROP!
 ---stay with your group and stay quiet!!
 --- calculate all densities after coming to sit down
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PART C:
 Mass of red block=
 Length =
 Width=
 Height=
 Volume =
 Density =

DENSITY LAB CONCLUSIONS

For #2 you will need these accepted values.
% error = measured – accepted
x 100
accepted
Water = 1.00 g/mL
Liquid A (isopropanol)= 0.786 g/mL
Liquid B (glycerin) = 1.26 g/mL
Solid sinker (lead alloy) = 11.40 g/cc
Red wood (alder) block = 0.4 g/cc

DENSITY
DENSITY = MASS
VOLUME
**this is a direct proportion**
As mass increases, volume increases (or as
mass decreases, volume decreases)
Units that measure density:
Solids: g/cm3
liquids: g/mL
gases:
g/L

**see density chart p. 38
Specific gravity
The density of a substance compared to
water’s density (1.0 g/mL)
 Float = density less than water
 Sink = density greater than water

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p. 40 (SHOW WORK AND INCLUDE
CORRECT UNIT)

#1. What is the density of a block of marble
occupying 310. Cm3 and a mass of 853
grams?
#2. Diamond has a density of 3.26 g/cm3 and
a volume of 0.351 cm3. Find the mass.
#3. What is the volume of a sample of
mercury having a mass of 76.2 grams and a
density of 13.6 g/mL?

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1.
2.75 g/cm3

2.
1.14 grams
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3.
5.60 mL
4) If a sample of lead is cut in
half, will its density change?
Explain why or why not.
No b/c mass AND volume both change
by the same factor
5) Find the density in grams/mL of a
liquid having a mass of 2 kg and a volume
of 2900 mL.
What might this liquid be?
(see p. 38)
Would it sink or float in water?


2000 grams / 2900 mL = 0.7 g/mL

It would float because it’s density is less
than water’s
SUMMARIZER: DENSITY 3-2-1
Name 3 measurements the density
formula involves.
 Give 2 units that measure density.
 Give 1 reason an object may float in
water.


Calculate the density of a gas with a mass
of 253 grams and a volume of 3.5 L.

ACTIVATOR:
Using the Density chart below, name 2
substances that will float in water AND 2
substances that will sink in water.
 Brass
8.55
 Gold
19.3
 Iron
7.8
 Uranium
18.7
 Ice at 0 C
0.92
 Wood
0.67
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Homework

Density handout front 1—13
back ODD
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1. 1.20 g/mL
2. 3.3 g/cc (could be Aluminum which has density of 2.7
g/cc)
3. 700 grams
4. 200 mL
5. 0.757 g/cc
6. 73 mL
7. 1.12 g/mL
8. 290 grams
9. 70 cc
10. 1.53 g/mL
11. 1.8 g/cc
12. 600 grams
13. 1.44 g/mL
BACK---ODD 1--20
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1.
3.
5.
7.
9.
11.
13.
15.
17.
19.
0.23 g/cc
0.14 g/cc
0.21 g/cc
0.27 g/cc
0.11 g/cc
2.0 g
2.7 g
2.6 g
90. cc
41 cc
EXTRA PRACTICE --DENSITY
1.
 2.
 3.
 4.
 5..
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30
2.0
2
3.0
SUMMARIZER—using the density
formula

How is density calculated?

How is mass calculated?

How is volume calculated?
ACTIVATOR

Calculate the volume of a block of wood
having a denisty of 0.78 g/cm3 and a mass
of 300 grams.
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WARM UP—DENSITY & GRAPHING
1.
Calculate the density of a liquid having a mass of 35 grams and a volume of
111 mL
2. Calculate the mass of a solid having a density of 2.5 g/cc and a volume of 3 cc.
3. Calculate the volume of a block with a mass of 9.0 grams and a density of 45
g/cm3.
4.
Find the density in grams/mL of a liquid having a mass of 3.4 kg and a volume
of 1.0 L.
5.
If a sample of gold is cut in half, would its density change. EXPLAIN WHY
OR WHY NOT.
ANSWER THE FOLLOWING QUESTIONS USING THE DATA TABLE BELOW:
MASS (g)
VOLUME (mL)
3.0
15.0
4.0
10.0
5.0
6.0
6.
7.
8.
9.
Calculate slope of the graph’s line.
Is this a direct or indirect relationship?
What is the responding variable?
What is the independent variable?
SUMMARIZER

Describe how the density is measured for
an irregular shaped solid VS. a
rectangular shaped solid.
p. 42 #5
 p. 54 #1, 2
 p. 57 #7-10
 p. 59 # 13b,c 14a,b 17-19, 22a,b
32b, 33b

ACTIVATOR

Put the object’s in the lab in order of least to
greatest density:
Water = 1.00 g/mL
Liquid A (isopropanol)= 0.786 g/mL
Liquid B (glycerin) = 1.26 g/mL
Solid sinker (lead alloy) = 11.40 g/cc
Red wood (alder) block = 0.4 g/cc
Which ones would sink in water? Which ones
would float in water?
QUIZ-- DENSITY= mass/volume
REMEMBER SIG FIGS AND UNITS!!
SHOW WORK!!
1. Calculate the density of a solid having a
mass of 45 grams, a length of 2 cm, a width
of 3 cm, and a height of 1 cm.
2. An object’s density is 3.6 g/cc. It is put into
a graduated cylinder initially having 25.0
mL. The water level rises to 25.2 mL.
What is the object’s mass?
3. Find the volume of an object with a mass
of 25 kg and a density of 5 g/mL.
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