DensityMiss FoggFall 2015

How can you tell the difference?

Gold (Au):19.32 g/cm3

Pyrite (FeS):5.01 g/cm3

Minerals Properties• Color• Streak • Luster• Crystal form• Hardness• Cleavage• Fracture

•Density

Density

• Density is a property of all matter that is the ratio of an object’s mass to its volume.

Triple Beam BalanceUsed to measure the mass of objects in grams (g)

Determining Mass

1. Place object on pan

2. Move riders along beam, starting with the largest, until the pointer is at the zero mark

Check to see that the balance scale is at zero

Triple Beam Balance1. Place object on pan

2. Move riders along beam, starting with the largest, until the pointer is at the zero mark

3. Read the mass just as you would a ruler (all certain digits and one uncertain digit between the lines)

Read Mass

_ _ _ . _ _ g2 7 2 ? ?

Read Mass More Closely

_ _ _ . _ _ g2 7 2 0 9

Measuring Liquid Volume

Always read volume from the bottom of the meniscus.

The meniscus is the curved surface of a liquid in a narrow cylindrical container.

Avoid Errors in MeasurementMeasure volume looking straight at the meniscus to

avoid parallax errors

Correct: Viewing the meniscusat eye level

Incorrect: viewing the meniscusfrom an angle

Use the graduations to find all certain digits

There are two unlabeled graduations below the meniscus, and each graduation represents 1 mL, so the certain digits of the reading are…

52 mL.

Estimate the uncertain digit and take a reading

The meniscus is about eight tenths of the way to the next graduation, so the final digit in the reading is .

The volume in the graduated cylinder is

0.8 mL

52.8 mL.