Density of different materials

Chem Catalyst

Chem catalyst

1. How can a ship made out of steel (more dense than water) carrying crude oil or containers full of goods (more dense than water) float on water?

2. Why do these people have an easier time floating on the water than somebody at the local swimming pool?

Goals

• Determine densities of regularly shaped objects

• Determine the difference between density of freshwater and saltwater

• Differentiate between density of components and density of the whole

DENSITY OF THE MATERIAL IN A TIN CAN

Volume equations of regular shapes

• Cylinder: V = πr2h

• Pyramid: V = ⅓Bh

• Rectangular Prism: V = Lwh

• Cone: V = ⅓πr2

• Sphere: V = ⁴⁄3πr³

What do the symbols mean?

V = volumer= radius of a circleB = area of the baseh = height (length perpendicular to the base)L = lengthw = width

Length, width and height are measurements perpendicular to each other

Finding the Radius

• Use circumference and diameter to find radius, do not EYEBALL it!

1.Use string to determine circumference

2.Divide the circumference by π to get diameter

3.Divide diameter in half to get radius

Procedure

For each object given:

1.Describe the shape of the container:2.Describe object or name the contents3.State the equation to find the volume of the

shape of the can:4.Determine which measurements are needed

to calculate the volume of the can

Procedure, part 25. For each measurement, identify the unit of measure to be

used:

6. Perform measurements and list in the chart below with the appropriate units

7. Calculate volume of object

8. Determine mass of object (!!warning!!) Some objects have the mass measurement on the label. DO NOT PUT LARGE OBJECTS on digital scales

9. Determine the density of object

Objects Chart

Object 1 (Describe__________)Measurement Description

Value of meas. (#)

Unit Description

Obj 2 (Describe ____________)Measurement Description

Value of meas. (#)

Unit Description

Calculations:

Density value, with units:

Calculations:

Density value, with units:

Determine the density of tap water and saltwater

• Goggles are needed for this lab(Why?)Materials needed– 100 ml graduated cylinder– 2 identical 100 ml griffin beakers– 50-60 ml of tap water– 4 grams of salt– Stirrer rod– Hot plate– thermometer

Steps to be accomplished

1. Determine the mass of an empty beaker2. Determine the mass of 50-60 ml of tap water3. Determine the volume, density of 50-60 ml of

tap water4. Heat up to 30⁰ C and dissolve all salt into 50-60

ml of tap water.5. Determine mass, volume and density of

saltwater solution6. TURN OFF THE HOT PLATE, clean and put

equipment back

Salt water

Type of Water

Volume Mass Density Temp.

Tap Water

Before heating

Saltwater solution

30⁰

Make sure values for saltwater are accomplished After Heating

Remember

• Turn off hot plate when you are done!!!

• Rinse and put away glassware

• Put goggles away in UV cabinets