DENSITY What’s Density? Tell me everything you think you know about Density? Try!!!

Let’s talk about Density What’s more dense…a bowling ball or a volley ball of equal size? The bowling ball of course! But why? Because it has more particles squeezed in the same amount of space! *Density is… a physical property that describes how much matter is packed in a given space (volume).

Let’s Talk About Density… Do you remember what the density of water is from 7th grade? It is measured by taking the mass per volume ratio. In other words divide the mass by the volume. *Density = Density of water is 1 g/cm3 Mass Volume

Remember… Mass = how much matter is in an object. Volume = how much space an object takes up. Remember what weight is? Weight is how much gravity is pulling on an objects mass!

DENSITY Let’s talk about units for a minute… For mass: kg, g, mg For volume: cm3, L, mL Why is cm cubed (to the 3rd power)? Because cm3 = length x width x height 1cm3 = 1ml or… For Density: g/cm3 or kg/ml or mg/cc or kg/cm3 cc = cubic centimeter

*Recognizing Units Copy down all 10 examples and determine if they are density, mass or volume? 43 g/cm3 800 kg 456 cm3 77 mg/cc 762 ml 67 mg 31 g/liter 212 g 100 cc 67 mg/ml Density Mass Volume volume 10. Density

This is how we will solve ALL our word problems!!! So this is… DUFAS and… This is how we will solve ALL our word problems!!!

How DUFAS works… All problems will be worth 5 points. You will get 1 point for every DUFAS step. So…correct answers are only worth 1 point!

DUFAS D is for Data U is for Units F is for Formula (Write down all the important Data in the problem) U is for Units (Write down all the units in the problem) F is for Formula (set up the correct formula) A is for arrange the formula (re-arrange it if you have to and plug in numbers) S is for Solve the problem

DATA: Copy this Example: Ashley’s 2.4 cm3 ear ring has a density of 19.3 g/cm3. What is the earing’s mass? What is the important Data in this question? V = 2.4 cm3 D = 19.3 g/cm3 What are we looking to solve for here? m = ? g

UNITS: Example: Ashley’s 2.4 cm3 ear ring has a density of 19.3 g/cm3. What is it’s mass? Write down all the CORRECT UNITS in this problem!!! V = cm3 D = g/cm3 m = ?

FORMULA: Example: Ashley’s 2.4 cm3 ear ring has a density of 19.3 g/cm3. What is it’s mass? You must write the formula for EVERY problem. *The Power Triangle will help you to do this! Draw a triangle like this one!

How to use the Power Triangle m v What is the formula for Density? = So how do we set up the power triangle? So what is the formula for volume? *What about mass? D x V m D m D v

Arrange: Example: Ashley’s 2.4 cm3 ear ring has a density of 19.3 g/cm3. What is it’s mass? New Formula is M=D x V D= 19.3 g/cm3 V= 2.4 cm3 m=(19.3 g/cm3) x (2.4 cm3)

Solve: Now you need to substitute the data into the arranged formula to SOLVE. m = D * V m =(19.3 g/cm3)*(2.4 cm3) V = 2.4 cm3 D = 19.3 g/cm3 m = ? g m = 46.32 g What happened to the cm3? They canceled each other out!

*Lets Practice using DUFAS! 1.) A 42.6 g gold ring has a density of 19.3 g/cm3. How much space is it taking up?

*Lets Practice using DUFAS! 1.) A 42.6 g gold ring has a density of 19.3 g/cm3. How much space is it taking up? 2.) A 257.8 cm3 man has a density of 11 kg/cm3. What is his mass? 3.) What is the density of a 52.1 cm3 block of ice that has a mass of 47.93 g?

*Lets Practice using DUFAS! 2.) A 257.8 cm3 man has a density of 11 kg/cm3. What is his mass?

*Lets Practice using DUFAS! 3.) What is the density of a 52.1 cm3 block of ice that has a mass of 47.93 g?

Practice Answers 1.) m = 42.6 g D = m d = 19.3 g/cm3 v v = ? cm3 v = m v = 42.6 g = D 19.3 g/cm3 2.20 cm3

Practice Answers 2.) m = ? kg D = m d = 11 kg/cm3 v v = 257.8 cm3 m= v*D m = 257.8 cm3 * 11 kg/cm3 = 2835.8 kg

Practice Answers 3.) m = 47.93 g D = m d = ? g/cm3 v v = 52.1 cm3

Density Calculations 2260 g 25 cm3 1 g/cc 4.9 g/ml 0.79 g/L 1284 kg 20 cm3 13.6 g/cc

The Density Column Lab

Using Density to Predict Position *If we put a solid into a liquid, and the solid is more dense than the liquid it will *If the liquid is more dense then the solid will *The same thing goes for all liquids. The least dense floats on top of more dense. sink Float

Question… If the lead weight is dropped into the beaker of water… will it sink or float? d= 11.4 g/ml What will happen if it is dropped into the mercury? mercury d = 13.5 g/ml water d = 1.0 g/ml

Alcohol 0.80 g/ml Veg. Oil 0.90 g/ml Water 1.00 g/ml ALL solids have the same volume of 15.6 ml Masses: pine = 5.4g acrylic = 17.3g steel = 128.5g wax = 9.8g pvc = 13.7g Calculate the densities of the five substances and predict where they would sink to in the density column. Take two places past the decimal. Alcohol 0.80 g/ml Veg. Oil 0.90 g/ml Water 1.00 g/ml Corn Syrup 1.20 g/ml Draw the density column (in the middle) with it’s densities (on left side)

ALL solids have the same volume of 15.6 ml Masses: pine = 5.4g acrylic = 17.3g steel = 128.5g wax = 9.8g pvc = 13.7g .34 g/ml .62 g/ml Alcohol 0.8 g/ml .87 g/ml Veg. Oil 0.9 g/ml Water 1.0 g/ml 1.1 g/ml Corn Syrup 1.2 g/ml 8.23 g/ml

Explain what happens to the mass, volume and density of Aluminum foil when it is crumpled up? Will it increase, decrease or stay the same? The Mass will… 2. The Volume will… 3. The Density will…

Explain why it will increase decrease or stay the same in a sentence or two. Mass The mass will stay the same! Due to law of conservation of mass! Volume 2. Volume will decrease b/c it is getting smaller. Density 3. The density will increase. More mass squeezed in a smaller space.

No it is not pure gold. It’s less dense than gold. Density 101 1. A gold-colored ring has a volume of 1.12 ml and a mass of 18.9 grams. Is the ring pure gold? (The density of pure gold is 19.3 g/ml.) D= M/V Density= 16.87 g/ml No it is not pure gold. It’s less dense than gold.

Density 101 2. What volume would a 0.871 gram sample of air occupy if the density of air is 1.29 g/liter? V= M/D .67 liters

Yes, pumice will float on water b/c it is less dense. Density 101 3. Pumice is volcanic rock that contains many trapped air bubbles. A 225 gram sample occupied 236.6 ml. What is the density of pumice? .95 g/ml 3a. What’s the density of water? 1 g/cm3 or 1 g/ml 3b. Will pumice float on water? Yes, pumice will float on water b/c it is less dense.

Volcanic Rock Pumice Pumice in Water

Density 101 4. A cup of sugar has a volume of 237 ml. What is the mass of the cup of sugar if the density is 1.59 g/ml? M= D x V M= 376.83 g Complete the Density Block Lab here!

Density Review use DUFAS to solve 1. A student finds a rock on the way to school.  In the laboratory he determines that the rock takes up 22.7 mL of space, and has a mass of 39.943 g.   What is the density of the rock? 2. The density of silver is 10.49 g/cm3.  If a sample of pure silver has a volume of 12.993 cm3, what is the mass? 3. A screwdriver has the density of 5.5 grams per cubic centimeter.  It also has the mass of 2.3g. How much space does the screwdriver take up? D= M/V 1.75 g/ml M= DxV 136.29 g V=M/D .41 cm3

*Density Practice DUFAS Problems Spectrum Text page 56 (1-2, 6-9) 1.Density of tin 7.30g/cm3 2. 3.26 g/cm3 3. 1.4 x 10-4 g/cm3 (gas) 4. 11.30 g/cm3 (Lead) 5. 0.670 g/cm3 6. 512 grams 7. 400 grams 8. 36 cm3 9. 0.029 cm3

Density Calculations 2260 g 25 cm3 1 g/cc 4.9 g/ml 0.79 g/L 1284 kg 20 cm3 13.6 g/cc POM Quiz I