Density

Warm Up: (5 min)1. What is density? What is

a job that requires knowledge about density?

2. What is happening in the picture to the right?

3. If I have a can of coke and I put it in a bowl of water, will it sink or float? What about a can of diet coke?

Today’s Notes (UNIT 2!!!) HAPPY OCTOBER

Title the page: Density

Date in upper right cornerNo talking while I’m talkingRaise your hand and wait to be called

on before you speak

TermsDENSITY (D): an object’s mass per unit

volumeLOW DENSITY (less than 1.00) – object floats in waterHIGH DENSITY(greater than 1.00) – object sinks in water

MASS (m): the amount of matter in an objectVOLUME (V): the three dimensional (3-D)

space an object occupies

Definition of DensityDensity: the amount of matter per unit of volume of an object

But what does that really mean?

Compare Thing 1 and Thing 2

Thing 1 Thing 2

Which of these has more matter? Which has more volume?So which one is the most dense?

THING 2SAME

VOLUMETHING 2

Compare Thing 1 and Thing 2

Thing 1 Thing 2

Matter Matter Volume Volume

Less dense

More dense

Compare Thing 3 and Thing 4

Thing 3 Thing 4

Which of these has more matter? Which has more volume?So which one is the most dense?

More dense

Less dense

THING 3

THING 4

SAME MATTER

Definition of DensityDensity: the amount of matter per unit of space of an object

But what does that really mean? (2 MINS, 2 SENTENCES)

How compact or packed together the matter is in the space of an object.

Apply it to real life:

More sugar Less sugar

What makes Coke different from diet Coke?

So what can we conclude about density?

More dense Less dense

Liquid Layers – Check it out!

• Which liquid has the highest density?

• Which liquid has the lowest density?

• Which liquid has the middle density?

Can you tell the density of something by looking at it?

Definition of Density• Density: the amount of matter per unit of

volume of an object

Matter: per: Space:Mass Volume

Formula for Densityp = m

V TERM VARIABL

EUNITS

Density D or p g/mL OR g/cm3

Mass m gVolume V mL OR cm3

Units1. What other Units of mass do you know?2. Units of VOLUME and DENSITY match up:

Volume in (mL) Volume in (cm3)

Density in (g/mL) Density in (g/cm3)

Example 1

Osmium is a very dense metal. What is its density if 50.00 g of the metal occupiesa volume of 2.22 cm3?

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Solution

p = mass = 50.00 g = volume 2.22 cm3

= 22.522522 g/cm3 = 22.5 g/cm3

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Will the Osmium float or sink in water?

In the problem we calculated Osmium had a density of 22.5 g/cm3

Remember the density of water is 1.00 g/cm3

22.5 g/cm3 > 1.00 g/cm3

Osmium is MORE dense therefore it will SINK

Independent Practice• Density Practice 1• Class Set!!!• Show work on paper• Complete only the front side• DUE AT THE END OF CLASS TODAY

Section 2-Complex Word Problems

Warm Up: (5 min)Turn in 3 problems

The density equation is p = m V

1. What would the equation look like if you were solving for mass (m)?

2. What would the equation look like if you were solving for volume (V)?

HINT: move the letters around

Today’s NotesTitle the page: Complex Density Problems

Date in upper right cornerNo talking while I’m talkingRaise your hand and wait to be called on

before you speak

Two Types of Complex Problems

1.Rearranging Equation Problems2.Volume of submerged objects

Class Overlook:• A quick example of both types • Work time

Practice 1 : RearrangingDo NOT copy the problem

Show your work in your notes1. Water has a known density of 1.00 g/mL.

Will Cray wants to know exactly how many mL of water are in his glass so he weighs the glass and finds the water inside has a weight of 30.9 g. What is the volume of the water in his glass?

Answer 1V = m V = 30.9 g V = 30.9

mL p 1.00 g/mL

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Practice 2: Submerged Objects

What is the density of 48 g of a metal if the metal raises the level of water in a graduated cylinder from 25 mL to 33 mL?

33 mL 25 mL

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Solution 2Volume (mL) of water displaced

= 33 mL - 25 mL = 8 mL

D = mass = 48 g = volume 8 mL

= 6 g/mL

Independent Practice1. Complete density practice 12. Complete density practice 2 (backside)3. Complete three problems on projector slide

(ON SEPARATE PAPER - - THEN STAPLE! & put on INBOX Table)

DO NOT COPY PROBLEMSSHOW WORK

IF YOU FINISH THAT: If you finish those come get your homework from me and you can work on that in class

Practice Problems – Rearranging Show work on a separate sheet

Do NOT copy the questions1. Will Cray takes the same glass and fills it

with orange juice so it is at the same volume (30.9 mL). The OJ weighs 61.8 g. What is the density of the OJ?

2. Without a balance we can calculate the weight of a liquid if we know its volume and density. What is the mass of 11.2 mL of a liquid with a density of 6.3 g/mL?

3. Calculate how many milliliters of a liquid are in the beaker given the following information:

• The beaker weighs 50 g• The beaker plus liquid weighs 64 g• The density of the liquid is 7 g/mL

Turn InWork on a separate sheet for Density Practice 1 and Density Practice 2 and Practice Problems – Rearranging

TURN IN DENSITY 1 & 2 ON INBOX TABLEGrab a HW assignment from stool by word

wall (DENSITY 3)

NAME, STAPLE TOGETHER, TURN IN

HomeworkHalf-Sheet Density Practice 3,

complete by next class

100% STOOLS UP AT BELLPush Chairs In