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 )

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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

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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

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Is 14-carat gold pure gold? Why or why not?!