Density - Wikipedia
Density is the mass of any material per unit volume. Gases always have much lower density than the condensed phases. Most materials have a lower density of . The density of air or atmospheric density, denoted ρ (Greek: rho), is the mass per unit volume of Earth's atmosphere. Air density, like air pressure, decreases with increasing altitude. It also changes with variation in atmospheric pressure, temperature and The following table illustrates the air density–temperature relationship at 1. The density, or more precisely, the volumetric mass density, of a substance is its mass per unit The density of a material varies with temperature and pressure. . Knowing the relation between excess volumes and activity coefficients of the.
Project the animation Liquid Water. Water molecules are always moving. But on the average they are packed the same throughout. Therefore, the ratio between the mass and volume is the same, making the density the same.
This is true no matter the size of the sample or where you select your sample from. Extend Have students consider whether the density of a large piece of a solid substance is the same as the density of a smaller piece. Give students time to calculate the density of each of the three samples drawn on their activity sheet and answer the related questions.
Exploring Our Fluid Earth
The density of a liquid is the same no matter what the size of the sample. Could this be true for solids, too? Calculate the density of each of the three samples to find out. The density of a solid substance is the same no matter how big or small the sample.
- Density of air
- Temperature Affects Density
Sample A has a mass of g. What is the density of Sample A?Gas Density and Molar Mass Formula, Examples, and Practice Problems
What is the density of Sample B? If water were used instead of mercury, the height of the column equivalent to normal pressure would be The Gas Laws The example of the gas-filled balloon can also be used to explore the basic gas laws see also Appendix D, p.
Density of Water
In the following, lets assume that the balloon is tight, so that the amount or mass of air in it stays the same: With density being the ratio of mass per volume, the gas density of the balloon thus varies only with its volume when mass is held constant.
If we squeeze the balloon, we compress the air and two things will happen: Since density is mass over volume, and the mass stays constant, the rise in density means that the volume of the balloon decreases: Explore Have students try adding cold and hot water to room-temperature water.
Question to investigate Is there a density difference between hot and cold water? Materials for each group Cold water colored blue in foam cup Hot water colored yellow in foam cup Room-temperature water in clear plastic cup colorless 2 droppers Teacher preparation Add ice to water to make very cold water.
Half-fill one foam cup with cold water no ice cubes and another with hot water for each group. Add 2 drops of yellow food coloring to the hot water and 2 drops of blue food coloring to the cold water.
Distribute the set of 3 cups to each group. Procedure Fill one dropper with blue cold water. Poke the end of the dropper about halfway into the colorless room-temperature water.
Temperature Effects on Density | Sciencing
While observing from the side, very gently squeeze the dropper so that the cold water slowly flows into the room-temperature water. Fill another dropper with yellow hot water. Poke the end of the dropper about halfway into the room-temperature water. While observing from the side, very gently squeeze the dropper so that the hot water slowly flows into the room-temperature water.