Pure Substances
What is a pure substance?
Matter with a composition that is always the same.
What is a mixture?
Two or more substances that are physically blended but do NOT combine chemically.
What is an acid?
A substance that promotes a chemical change and creates salt water with a base.
What is a base?
A substance that promotes a chemical change and creates salt water with an acid.
O and HCL are pure substances. How would you classify O and HCL?
O (oxygen) is an element and HCL (hydrogen chloride) is a compound.
What is an element?
A substance made of only one kind of atom.
What is a HOMOGENEOUS mixture? Give an example.
Two or more substances are evenly mixed, but not bonded together. Examples: air, sea water, salt water, coffee, and steel.
What numbers on the pH scale represent an acidic substance?
0 (strong acid) to 6 (weak acid)
What numbers on the pH scale represent a basic/alkaline substance?
8 (weak base) to 14 (strong base)
Why can you separate substances that are part of a mixture?
Because they are physically blended and not chemically bonded together.
What is a compound?
A substance made of two or more different elements that are chemically joined in a specific way.
What is a HETEROGENEOUS mixture? Give an example.
Two or more substances that are not evenly mixed. Examples: trail mix, pizza, oil and water, soil, and blood.
List the following substances from LEAST acidic to MOST acidic.
-Ammonia (pH 12)
-Lemon juice (pH 2.5)
-Distilled water (pH 7)
Ammonia (least acidic), Distilled water, Lemon juice (most acidic)
Sam dipped red litmus paper into a substance with a pH of 9.5. What color will the red litmus paper turn?
Blue
A solution.
Give an example of an element.
Examples: Gold; Oxygen; Hydrogen; Nitrogen; Boron; Neon; Aluminum; Helium; Carbon, Copper; [any other element listed on the periodic table].
Can you separate a mixture? Explain.
Yes, a mixture can be separated using physical methods because its components are not chemically bonded
On the pH scale, battery acid has a pH of 0. Which of these phrases describes battery acid?
a) Highly basic
b) Highly acidic
c) Slightly basic
d) Slightly acidic
b) Highly acidic
Anna has a basic solution. She then added an acid solution to her basic solution. Describe how the pH will change.
The pH will begin to lower.
What forms when mixing an acid and a base?
Water and a salt.
Give an example of a compound.
Examples: Water; Carbon dioxide; Sodium chloride (table salt); Methane; Glucose; Ammonia; Sulfuric acid; Hydrogen peroxide; Propane; Acetone; [any other acceptable compound].
What three different ways can you separate a mixture?
1. Filtration
2. Magnets
3. Evaporation
What are properties of acids?
*Tastes sour
*Turn blue litmus paper RED
*React with metals to produce hydrogen
*Contain hydrogen ions (H+)
What are properties of bases?
*Taste bitter
*Turn red litmus paper BLUE
*Feel slippery
*Contain hydroxide ions (OH-)
Neutralization