Classifying Matter
Classify pure substances or mixtures based on a description.
Pure substance has a constant composition (constant melting/boiling point).
Mixtures are two or more substances combined physically.
Is milk a pure substance? If not, what is it?
It isn't, It contains various components (water, fat, protein, and sugars). Which will make it a mixture.
Malleability- What materials tend to be malleable?
Gold
What are the two methods of using physical properties to separate mixtures.
Filtration and evaporation
Which is more reactive, oxygen or nitrogen?
Oxygen
Whats the difference between elements and compounds?
Elements consist of one type of atom
Compounds consist of two or more different types of atoms combined together
Identify homogeneous solutions and colloids. And an example for both.
Homogenous solution is completely dissolved. Ex- saltwater
Homogeneous colloids are phases of smaller particles. Ex- milk
Hardness- How does the "scratch test" work?
Scratch a surface harder and harder until a scratch forms. It shows how hard a surface is.
When can you use filtration to separate mixtures (heterogeneous or homogeneous)?
Heterogeneous
What are the 4 "clues" that a chemical change has taken place?
1. change in color 2. production of gas 3. formation of precipitate 4. changes in temperature
(True or False) Do compounds have different properties than the substances from which they're made?
True
Identify heterogenous mixtures as suspension. And give an example.
Settles out apon standing. Ex- Flour in water
Melting and boiling points- What's the m.p. and b.p. for water? What state of matter will it be in at room temperature based on the m.p. and b.p.?
M.p.- 0 degrees C B.p. 100 degrees C
The state of matter based on m.p. is LIQUID
The state of matter based on b.p. is Gas
Describe the process of distillation. How does it work?
It's the process of separating a liquid from a mixture.
It works by heating a liquid mixture to create vapor.
What's the difference between a chemical change and a physical change?
Chemical change: the composition of the matter CHANGES
Physical change: the composition of the matter STAYS THE SAME
Compounds aren't made of two or more elements joined in a fixed proportion.
False- Compounds ARE made of two or more elements
Viscosity- How fast do materials with a high viscosity flow? How fast do materials with a low viscosity flow.?
High viscosity- flows slow
Low viscosity- flows fast
Density- Describe the water displacement method. Find the density of an object just given its mass and volume.
Take a cylinder and fill it with water enough to over the object. Record the measurement. Then put the object inside the cylinder and remeasure it. Before object- after object.
Density = Mass divided by volume
Identify whether a physical change is reversable or irreversible.
Mostly reversable.
irreversible- cutting wood
reversible- melting ice
(True or False) The composition, and maybe properties, of mixtures can vary.
True
Conductivity- What would be a good conductor? What would make a bad conductor?
Good conductor- metal spoon
Bad conductor- Wood spoon
What are the 2 reasons why physical properties are useful?
1. Helps identify a material
2. Helps choose a material for a specific purpose
Give 2 examples of chemical properties- when can chemical properties be observed?
Flammability and reactivity
When the substance in a sample of matter is changing into different substances