Water has a density of 1.0 g/cm³(one gram per cubic centimeter). Objects that have a density greater than 1.0 g/cm³ will sink in water. Objects that have a density less than 1.0 g/cm³ will float in water. When you fill a graduated cylinder with water, there is often a curve instead of straight line at the top of the cylinder. This curve is known as a "meniscus."

Your challenge in this activity will be to accurately measure both mass and volume. Using this data, you will calculate density.

The formula for calculating density is: .

Materials:

• Balance scale
• Calculator
• graduated cylinder (large enough for objects to fit into)
• Pencil or pen
• Paper
• Water
• Variety of items with different densities

Safety concerns: Be sure to follow all chemical and glassware object safety rules that are specified by your teacher in all general laboratory experiences.

Procedures:

1. Select one item and predict whether it will sink or float in water.
1. Record your prediction.
2. Using the same item, determine its volume by using a graduated cylinder and water.
1. Fill the cylinder to a designated amount and record this starting point.
2. Gently drop in the item. Record the amount of water that was displaced by the item.
1. If the graduated cylinder is not large enough for the selected item, set a small container in an empty larger pan.
2. Completely fill the small container with water.
3. Gently drop the item into the water.
4. Water will spill out into the larger container.
5. Measure this water as the amount that is displaced = volume.
3. Using same item, determine its mass by weighing the item on balance scale. Record the mass.
4. Divide the mass by the volume to calculate the density and record the item's density.
5. Items having a density greater than1.0 g/cm³ will sink; items having a density less than 1.0 g/cm³ will float.
1. Organize items you tested into appropriate groups based on whether they sink or float.

Analysis:

1. How well did you predict which objects would float and which would sink in water?
2. What other items would you like to test to determine their density?
   • Get permission and try your other objects and calcuate their density.

Extension:

Try to find an object that has a density which is greater than 1.0 g/cm³ but will still float in water!