AP Chem Chapter 1 Flashcards
what is the scientific method
the process of studying natural phenomena, involving observations, forming laws and theories, and testing of theories during experimentation
what are the three main steps in the scientific method
- making observations
- formulating hypotheses
- performing experiments
what is a theory
a set of tested hypotheses that gives an overall explanation of some natural phenomenon
what is the difference between an observation and a theory
an observation is something that is witnessed and can be recorded. a theory is an interpretation, a possible explanation of why nature behaves a certain way
what is a natural law
a statement that expresses generally observed behavior
what is the difference between a theory and a law
a law summarizes what happens, a theory attempts to explain why it happens
what is the SI system
international system of units based on the metric system and units derived from the metric system
what is the difference between mass and weight
mass is a measure of the resistance of an object to a change in its state of motion
weight is a measure of the force that gravity exerts on an object
do all measurements have some degree of uncertainty
yes
true or false: we customarily report a measurement by recording to the first uncertain digit
true
what are sig figs
the certain digits and the first uncertain digit of a measurement
what is accuracy
the agreement of a particular value with the true value
what is precision
the degree of agreement among several measurements of the same quantity
what is a random error
a measurement has an equal probability of being high or low
what us a systemic error
occurs in the same direction each time; either always high or always low
under what circumstances is high precision among several measurements an indication of accuracy
if systemic errors are absent
do you round sequentially?
no. the number 6.8347 rounded to 3 sig figs is 6.83, not 6.84
do exact numbers ever limit sig figs
no
what is dimensional analysis
a method used to convert from one unit to another
what is the equation to find kelvin temperature
K = C + 273
what is the equation to find fahrenheit temp or celsius temp
F = 1.8C + 32
what temp is the same for both celsius and fahrenheit
-40
what is density
mass of a substance per unit volume of that substance
what is the equation for density
d=m/v
what is the density of water
1 g/cm3
does density depend on how much of a substance you have
no, it stays constant no matter how much u have
what is matter
anything that takes up space and has mass
volume and shape of a solid
both fixed
volume and shape of a liquid
definite volume, indefinite shape
volume and shape of a gas
neither fixed
what are the main characteristics of a mixture
has a variable composition
can be separated into pure substances by physical means
what are the two subcategories of mixtures
homogeneous and heterogenous
what is a homogeneous mixture
a mixture with visibly indistinguishable parts
what is a heterogeneous mixture
a mixture that has visibly distinguishable parts
what is another name for a homogeneous mixture
a solution
what are the two subcategories of matter
mixtures and pure substances
what is a pure substance
has a constant composition
what are physical changes
a change in the form of a substance, but not in its chemical composition
can physical changes be used to change break pure substances into elements
no
what are the 2 subcategories of pure substances
elements and compounds
what is an element
a pure substance that cannot be broken down into simpler substances
what is a compound
a pure substance that can be broken down into its component elements by chemical means
what is distillation
a method for separating mixtures based on the differences in volatility of the components
what does volatile mean
it refers to the ease with which a substance can be changed to its vapor
how does distillation work
- a mixture is heated
- the most volatile component vaporizes at the lowest temp; then it passes through a cold tube to condense back into a liquid in a separate container
what is filtration
a method for separating mixtures made of a solid and a liquid
what is chromatography
a method for separating mixtures that works with two phases of matter, a stationary phase (a solid) and a mobile phase (a liquid or a gas)
why does chromatography work
bc the components of a mixture have different affinities for the two phases and move through them at different rates
what is a chemical change
a change in which a given substance becomes a new substance or substances with different properties and different compositions
