12/12 B Day LEQ: How can we use density to tell if an element is pure? 1. What is one element that has similar properties to hydrogen? 2. Would you expect sodium (Na) to be malleable? 3. Why or why not? (Explain your answer!) 4. Would you expect xenon (Xe) to be ductile? 5. Why or why not? (Explain your
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12/12 B DayLEQ: How can we use density to tell if an element is pure?
1. What is one element that has similar properties to hydrogen? 2. Would you expect sodium (Na) to be malleable? 3. Why or why not? (Explain your answer!)4. Would you expect xenon (Xe) to be ductile?5. Why or why not? (Explain your answer!)
Today’s LEQ: How can we use density to tell if an element is pure?
By the end of today, you should be able to…1. SOLVE to find the density of an object using
the density equation.
2. Use data on density to determine if an element is pure
Focus Vocabulary:
77. Mass78. Volume
Activating Strategy
Which ring would you rather have?
14-carat 24-carat
Draw this in your notes:
=
Draw this in your notes:
=
MASS = how much matter is in an object (how many ATOMS are in something)
Draw this in your notes:
=
MASS = how much matter is in an object (how many ATOMS are in something)
VOLUME = how much space an object takes up (how BIG is the object?)
Volume: how much space an object takes up
Draw this in your notes:
=
MASS = how much matter is in an object (how many ATOMS are in something)
VOLUME = how much space an object takes up (how BIG is the object?)
DENSITY(how many atoms there are in a certain space)
More Dense Less Dense
BrainPop: Density
D =
MASS = grams (g)
VOLUME = milliliters (mL) OR centimeters cubed (cm )
DENSITY = grams per milliliter (g/mL) OR grams per centimeter cubed (g/cm )
3
3
SOLVE:Mass: 15 g Volume: 3 mL
15 g 3 mL
= 5 g/mL
M V
D =
SOLVE:Mass: 24 g Volume: 4 cm
24 g 4 cm
= 6 g/cm
3
33
SOLVE:Density: 4 g/mLMass: 12 g
12 g= 4 g/mL
WHAT NOW?!
?
D
M
V÷
x
÷
Density Triangle:
S
D
x
÷
How to use the triangle…
DMV=
1. When given mass and volume:
2. When given mass and density:
3. When given density and volume:
D × V = M
SOLVE:4 g/mL12 g
12 g
V = 3 mL
=
4 g/mL
12 g
4 g/mLV
SOLVE:16 g4 mL
16 g
S = 4 g/mL
=
4 mL
16 g
4 mLS
SOLVE:8 g/mL4 mL
8 g/mL
M = 32 g
4 mL
4 mL 8 g/mL = Mx
1.
2.
3.
4.
5.
200 g
100 g
16,000 g
150 g
625 mL
625 cm3
0.64 g/mL
0.8 g/mL
4,000 cm3
0.75 g/cm3
LAB TIME!
Using a triple beam balance scale:
http://www.youtube.com/watch?v=jknT_OKb6yM
LAB TIME!
1. Write the formula for density2. Fill in the density triangle3. Use the scale to measure and record
the MASS of each object4. Use your calculator to calculate the
density or the volume of each object (don’t forget the units!)
EVERY ELEMENT HAS ITS OWN
UNIQUE DENSITY!
WE CAN USE DENSITY TO
IDENTIFY ELEMENTS!
HOT Q: Unknown substance:Mass: 12.96Volume: 4.8
Density:________
What is the unknown substance?!
2.7
ALUMINUM!
Summarizer: Density of pure gold: 19.3 g/cm
Density of a 14-carat gold ring: Mass: 157 gVolume: 13.8 cm
3
3
Is 14-carat gold pure gold? Why or why not?!
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