DENSITY AND SPECIFIC GRAVITY

• A property of matter representing the mass per unit volume

• g/ml –liquid -grams/milliliters

• g/cm3 -solid -grams/centimeters cubed

• 1ml = 1cm3

• Must be in grams, centimeters, and milliliters *no other units allowed

To Find the Mass (numerator)

• Grams -mass

-solid -place item on balance scales

-liquid 1. find the mass of an empty cylinder

2. find the mass of the cylinder with the liquid in it

3. subtract the two readings = the mass of the liquid

To Find Volume (denominator)

• Volume -ml or cm3

• Use a cylinder for liquid and read the meniscus (lowest level of liquid in the cylinder)

Volume of an Irregular Solid

• Use water displacement for a solid 1. put water in a cylinder and read

2. drop a solid in the water and read again

3. subtract the two readings

continued

• Water weighs 1 gram per milliliter

• Water’s mass is 1 gram per milliliter

• Water’s density is 1 gram per milliliter

• Anything more dense than 1 gram per milliliter will sink in water

• Anything less dense than 1gram per milliliter will float on water

Volume of a Regular Solid

• Volume for a regular solid

using a meter stick, measure the height, width, and length

H x W x L = the volume

1 side x 1 side x 1 side = the volume of a cube

if all the sides are the same = the side cubed (g/cm3)

Review

• Volume of a rectangleL x W x H

Volume of a cylinder (radius = diameter/2)pi x R2 x H

Volume of a sphere 4/3 x pi x R2 (radius = circumference/pi/2)

Check in passbook for equations

Label for Density

• So, Density = g/cm3 or g/ml

Problems to Solve

• Density = ?cm3 = 5g = 15

(per means to divide) g/cm3

Grams = ?density = 6 g/mlml = 2

• Volume = 50cm3

Mass = 100grams

What is the density of this object

Volume = 32 liters

Mass = 40 centigrams (must change centigrams to grams before

completing the problem)

• Volume reading in cylinder

water only 4ml

water with rock8ml

mass = 12 g

Will it float or sink in water?

What is the density?