1. Significant Figure Rules and Accuracy vs. Precision
Unit 1

2. Significant Figure Rules
In any calculation, your answer cannot have more digits than the measurement with the least amount of digits given
All nonzero numbers are always significant (1,2,3,4,5,6,7,8,9)
Zeroes between two nonzero numbers are always significant (505 has 3 significant figures)
Zeroes at the end of a number that contains a decimal are significant (21,000. has 5 significant figures, has 5 significant figures)
Leading zeroes are never significant ( has two significant figures)
Zeroes at the end of a number without a decimal are not significant (300 has 1 significant figure)

3. Accuracy vs. Precision
Accuracy is a measure of how close a result comes to the accepted answer.
Precision is a measure of how close together several results are to each other.

4. Mixtures A mixture is a physical blend of two or more substances
This means the parts are not bonded together, therefore bonds must not be broken to separate them

5. Homogeneous vs. Heterogeneous
2 types of mixtures: Homogeneous and Heterogeneous
Homogeneous—the composition is the same throughout (also known as a solution)
Examples: Salt water, vinegar, stainless steel (mixture of iron, chromium, and nickel)
Heterogeneous—the composition is not the same throughout
Examples: Oil and water, ice water, chicken noodle soup

6. Separating Mixtures
Because they are not bonded together, separating mixtures does not require breaking bonds
Separating a mixture is a physical change
Heterogeneous mixtures are typically easier to separate
Filtration—process that separates a solid from a liquid in a heterogeneous mixture

8. Separating Mixtures
Separating a homogeneous mixture, though, requires manipulating the physical properties of the components of the mixture
Physical properties used to separate mixtures include: boiling point, freezing point, and melting point
Distillation is the process of separating mixtures based on differences in boiling point