chem h chap 1 test

qualitative

non-numerical, descriptive information that captures qualities, characteristics, and experiences

quantitative

numerical information that can be counted, measured

matter

anything that occupies space (having volume) and has mass

observation

made with 5 senses, qualitative and quantitative

hypothesis

reasonable prediction

scientific theory

most logical answers for why/how things happen

Law

predicts what happens / general summary of observation

scientific event

where something specific happens

Pure substances

elements and compounds

compound

2+ chemically combined

mixtures

heterogenous and homogeneous

heterogenous

colloids and suspensions

colloids

mixture where one substance’s particles are so small that it cannot be filtered, but it still reflects light

suspensions

mixture with a substance that has particle so big it sinks to the bottom (also reflects light)

chemical change

change in composition, energy transfer, odor, unexpected color change, precipitate (texture change) irreversible..

physical change

not chemical, reversible

distillation

separate liquid/homogenous mixtures by boiling point

evaporation

separating dissolved solid + liquid by boiling

filtration

used to separated undissolved solid + liquid (sand + water)

precision

how close data is to each other

how to calculate precision

1/2±certainty of each data point, if they overlap = precise

accuracy

how close data to actual value (or avg.)

how to calculate accuracy

½ ± certainty of actual value, if a data point lies in range, then all the data is accurate

law of conversation of mass

mass cannot be created or destroyed

% error

(actual - experimental)/ actual * 100

error margin

½

density

m/v

density of water

1g/ml

intensive prop (won’t change based on #of substance)

density, boiling/freezing point and appearance

extensive prop (dep. on amt)

mass, length, volume

good and bad R^s (determines accuracy on a graph)

0.8 to 0.9, 0.5

measuring volume for 50 and 100 ml

record to 1 decimal place

measuring volume for 10 ml and length

measure to 2 decimal places

leading zeros _____

are not significant

captive zeros are ____

significant

trailing zeros are significant only ___

if number contains a decimal point

exact numbers (determined by counting, not measuring) __

have infinite number of sig figs

rules for sig figs in mathematical operations (x and division)

round the final answer to same number of sig figs as the measurement with the least number of sig figs

rules for sig figs in mathematical operations ( - and + )

round the final answer so that it has the same number of decimal places as the measurement with the least number of decimal places