DENSITY

1.A substance has a volume of 2.0 cm₃ and a mass of 38.6 g. What is the density?

2.If 17g of brass occupy 2 cubic centimeters, what is the density?

9/10

DO THE FOLLOWING PROBLEMS IN YOUR NOTEBOOK

1.A substance has a volume of 2.0 cm₃ and a mass of 38.6 g. What is the density?

• D=M/V• Mass=38.6g• Volume= 2 cm₃

• D=38.6g/2 cm₃ • D=19.3

ANSWERS

2. If 17g of brass occupy 2 cubic centimeters, what is the density?

• D=M/V• Mass=17g• Volume=2 cm₃ • D= 17g/2cm₃ • D=8.5g/cm₃

ANSWERS

• Compare the density of a substance with the density of eater

• Specific gravity= density of substance

density of water • Example: specific gravity of

steel = 7.8g/ cm₃ 1.0 g/ cm₃ = 7.8 (steel is 7.8 times more dense than water)- If the specific gravity is less than 1, the object floats!

SPECIFIC GRAVITY

Substance Density (g/cm₃)

Acrylic 1.0-1.5Aluminum 2.5-2.9Brass 8.3-8.7Copper 8.7-9.1Oak 0.5-0.9Pine 0.3-0.5Polypropylene (plastic)

0.8-0.97

PVC 1.2-1.6Steel 7.7-8.1Water 1.0

DENSITY BLOCKS

• What will happen when a raw egg is placed in regular water? What will happen when it is placed in salt water?

• What will happen when to a lemon and a lime if placed in water?

• What will happen if the rind of the lemon and lime are removed and placed in water?

SO WHAT’S GOING ON?

• Egg in fresh water: an object that is more dense than water will sink

• Egg is salt water: salt is more dense than regular water and it can hold up the egg

• Salt ions bind with water molecules allowing the salt water to become more dense (increasing the amount of matter per space)

SO WHAT’S GOING ON?

• Lemon: floats• Lime: sinks• Lemon without rind:

still floats• Lime without rind: still

sinks • Mass of lemon:• Mass of lime:• Volume of lemon:• Volume of lime:

LEMONS AND LIMES?