CHEM 100: EXAM 1 CONTENT

Observation

Observation

Oh my god, that’s so cool- moving hands up and down, palms face up (what gesture)

Hypothesis

Hmmm, I wonder - put finger to chin

Experiment

Let’s do it - pump fist

Conclusion refuted

Back to the drawing board - make circular motion with finger vertically

Conclusion supported

Oh, so that’s why - move hands up and down palms face up

Observation definition

A statement that describes an event or object

Law

A statement or equation that can help predict the result of a similar situation

Theory

A statement that explains the ‘why’ of a phenomenon

Model knowledge of science

1. Core ideas

2. Frontiers of science

3. Pseudoscience

Core ideas

Concepts believed to be true, includes facts, laws, and theories

Frontiers of science

Advancements in technology and knowledge stemming from the core ideas

Pseudoscience

Ideas not based on science but are believed by certain groups (eg. flat earthers, creationism)

Experiment results contradict a theory

When experiment results consistently contradict a theory, that theory must be reviewed and revised

Scientific notation rules

• a * 10^x - where 0 < a < 10

• When making a smaller, make x bigger

• When making a bigger, make x smaller

Significant figure rules

• All non-zeroes are significant

• Zeroes after a dp are significant

• All numbers in scientific notation are significant

• Zeroes between two non-zeroes are significant

• Leading zeroes are insignificant

• Trailing zeroes before a dp are AMBIGUOUS, if there is a period it is non ambiguous
  

Multiplication and division rules

Answer uses the least sig figs as seen in the equation

Addition and subtraction rules

Answer uses the least decimal places as seen in the equation

Multiple operation rule

Perform PEMDAS, the LAST operation you do is the rule you follow (eg. you subtract a value in brackets and then multiply this by another value—you would use the least sig fig rule)

SI units

• Mass - kg

• Length - m

• Time - sec

• Temperature - Kelvin

• Amount of substance - mol

Positive prefixes

• Deca (1)

• Hecto (2)

• Kilo (3)

• Mega (6)

• Giga (9)

• Tera (12)

Negative prefixes

• Deci (1)

• Centi (2)

• Mili (3)

• Micro (6)

• Nano (9)

• Pico (12)

• Femto (15)

Starting a DA word problem

Circle the known unit, underline the unknown unit, and draw arrows for the conversion factor

DA rules

Unknown is the easiest to find, known and unknown are in the same statement, unknown = known sig figs

How to determine dps in measurements

Look at where the line ends; state which two values it is between; add a decimal place to the end

Density

d=m/v density is measured in g/cm³ or g/mL

Substance

Something that cannot be separated into different types of matter through physical processes; is either an element or compound—there can only be one type of compound for it to be considered a substance, or else it is a mixture

Mixture

Can be separated into different types of matter through physical means (filtering, evaporation), can be homogenous or heterogenous

Homogenous

Uniform mixture, looks the same throughout

Heterogenous

Non-uniform mixture, components are distinguishable

Physical changes

Changes that can be reversed

Chemical changes

Changes that cannot be undone or reversed (eg. combustion, oxidation)

Celsius to Fahrenheit

1.8C+32=F

Celsius to Kelvin

C+273.15=K