Test #1
All of the following is information you need to understand to apply to your science test.
Matter- all things are composed of particles of matter
- it takes up space(volume)
- it has mass(how much stuff is in it)
- can be in the form of a solid, liquid or gas
solid = particles are close together
- moving very slowly, low kinetic energy
- definite shape and volume
liquid = particles are spread out
- moving faster, medium kinetic energy
- definite volume
-no definite shape, takes the shape of its container
gas = particles spread far apart
-moving fastest, highest kinetic energy
-no definite shape or volume-will spread out to fill any size container
Solids, liquids and gases are states of matter. When they change from one state to another it is called a phase change.
Phase Change Chart |
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Endothermic Exothermic (Energy added) (Energy released) |
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Solid----Gas Gas ------Solid (Sublimation) (Sublimation)
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Solid------Liquid Liquid ----Solid (Melting) (Freezing) 0 C 0 C |
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Liquid-----Gas Gas ------Liquid (Boiling) (Condensation) 100 C 100 C
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While a substance is undergoing a phase change, its temperature remains constant. All the energy being added or removed is used up for the phase change, so the temperature does not change.
Density-the amount of mass in a given amount of space(volume)
-physical property- cutting a substance innto smaller pieces will not affect the density. Density will stay the same for each piece. Different shaped pieces will have the same density too.
-formula =mass/volume
-units(label) can be g/ml or g/cm
-most matter has its greatest density in the solid form.
This means the particles are packed tightly together in a
small amount of space.
- Density is affected by changes in temperature and pressure
A. Temperature increases, volume increases, particles spread out or expand, density decreases =inverse relationship between temperature and density, they are opposites.
B. Pressure increases, volume decreases, particles are packed together more tightly or contract, density increases =direct relationship between pressure and density, they do the same thing.
water is the exception
-its greatest density of 1.0g/cm is in the liquid state at
4 C
-ice floats =less dense than liquid water. As water freezes at 0 C, its particles spread out causing the volume to increase, making the density go down. Lower density makes ice float.
-on a graph, water’s density line cuts the graph in half. Any density line above it means that object will sink in water. Any density line below it, means that object will float in water.
Physical Properties(see attached sheet for complete list and descriptions)
-is the ability of a substance to undergo or resist chemical changes
ex-something is resistant to flame. It won’t burn, it is not flammable.
Physical change vs. Chemical change
Physical change is a change in one or more of the physical properties-like appearance, density, state of matter (solid, liquid or gas).
Ex-melting ice to make liquid water is a physical change
Chemical change is a change substances undergo when they become a new or different substance-like iron rusting, or baking soda and vinegar producing carbon dioxide gas. Chemical changes are not reversible like physical changes are.
If a material can dissolve in something else(like salt in water) that material is said to be soluble. If one of the materials is a liquid, then the product is called a solution.
(Recall the Space Matters lab with the salt in water and the alcohol in water)
The material that dissolves in something else is called the solute. (salt, alcohol)
The material that makes it dissolve is called the solvent(water).
The materials can dissolve because there is space available between the particles of the solvent for it to “fit in”. If the material does not dissolve, there is no more room between the particles and the solution is called saturated(full).
Temperature affects how quickly materials dissolve. The higher the temperature, the faster an object will dissolve. Particles are moving rapidly, spreading out creating more space for material to dissolve in.