Vocabulary
What is the mass per unit of a substance?
Density
A gas in a balloon has a definite ____ even when the temperature changes.
Mass
True or False. Ketchup has a higher viscosity than water. If False Why?
True
New substances form during a physical change. True or False
False. New substances form in a chemical change.
What happens to a car tie in the summer compared to the winter?
Due to thermal expansion, the air in the tire expands during the summer and deflates during the winter.
What is the force of attraction between particles of the same kind
Cohesion
A substance that has a definite mass and definite volume but not definite shape is a
Liquid
What type of substance has a specific pattern of atoms and a specific melting point?
crystalline solid
Name a characteristic property?
Boiling Point
What is an attractive force between two objects with mass
Gravity
What is the attractive force between unlike substances that holds them together
Adhesion
If some of the milk from a pitcher was poured into a glass, the milk in the pitcher and the milk in the glass would have the same
Density
True or False. . To lubricate the parts of a machine, you would use a substance with a very low viscosity. If False then Why.
False. You would use a highly viscous material.
What is the law of conservation of mass?
Matter cannot be created or destroyed.
How is the motion of molecules in a liquid different from the motion of molecules in a gas?
The molecules in a liquid have enough energy to overcome some cohesive force, but not all of it. They can move some. The molecules in a gas have more energy than those in a liquid, so they can overcome cohesion and move about freely
What is the amount of force exerted on an object per unit of area
Pressure
If you were to land on Mars, why would your weight change but not your mass?
Weight measures gravitational force on an object, and mass measures the amount of matter. There is less gravitational force on Mars so I would weigh less, but the amount of matter in my body would stay the same.
Soap increases the surface tension of water? True of False
Soap decreases the surface tension of water.
If baking soda and vinegar react to make carbon dioxide gas, is there less matter when the reaction is done? Why?
No, because the law of conservation of mass states that matter can neither be created nor destroyed. There may be less matter in the container, but the molecules have regrouped in the chemical change and are now in the air.
If the mass of a block of wood is 40 g and its volume is 50 cm3 , what is its density?
0.8 g/cm3
What is Viscosity?
a liquid’s resistance to flow
Why is a rubber hose less flexible when it is cold than when it is warm?
When the hose is cold, the molecules have less energy so they move less, making the hose more rigid. When the molecules are warm, they have more energy so they move more. This makes the hose more flexible
What happens to a substance when the molecules lose so much energy that they can only vibrate and become completely subject to cohesion?
It Freezes
Identify the following changes as either chemical or physical: dissolving; rusting; burning; sublimation; color change; bubble formation; melting; evaporation.
dissolving—physical; rusting—chemical; burning—chemical; sublimation—physical; color change—chemical; bubble formation—chemical; melting—physical; evaporation—physical
According to Boyle’s law, when the pressure on a gas increases, _______?
its volume decreases