chem unit 1 study guide

erlenmeyer flask/beaker

can record to the 50s (like 250), not accurate or precise, looks like a clear cup

volumetric flask

can only record one measurement (smtg like 100.00 mL) but it is VERY precise and accurate with this measurement, looks like tube that expands into a bigger base

burette/pipette

can record to the 10ths and 1s (6.52), precise and accurate, looks like a tube with a rectangle on the bottom with a triangle attached

graduated cylinder

can record to the 1s (2.50 mL), accurate and precise, looks like a cup with a circle on the bottom

precision

being exact/all bullets in the same place but not necessarily on bullseye

accuracy

being close or true to a correct value/bullets are averagely spaced around the bullseye

percent error

what accuracy is assessed with...eq: actual-true
------------- x100%
true

standard deviation/95% confidence interval

what precision is assed with...annoying to do by hand so use excel

systematic error

Error that shifts all measurements in a standardized way. Decreases accuracy. Can result in bias

random error

Error that is due to chance and is not standardized. Decreases precision.

scientific method

s series of steps scientists perform when completing an experiment

ask a question

1st step of scientific method, provides u with stmg u wish to know

do research

2nd step of scientific method, find out what is already known

construct hypothesis

3rd step of scientific method, make an educated guess about what the results of the experiment will be

design a procedure

4th step of sci method, develop step by step directions

collect data

5th step of scientific method, gather your info

analyze data

6th step of sci method, assess what your data means; this might involve calculations or graphs

draw conclusions

7th step of sci method, tells the story that your data provides you with and answers your original question

cyclical process

goes over and over again, what the sci method is, when experiments end new questions rise and the process begins anew

how we r suppose to do lab write ups

purpose statement (contains "to"), hypothesis ("if...then...because..."), materials list, procedure, data (contains tables, calculations, and graphs), results (para form), conclusion (restate purpose, summarize procedure, restate results)

significant figures

all known digits in a measurement plus one estimated digit

which #s are sig figs

all numbers 1-9

sandwiched zero-s

counts as sig fig (1003 has 4 sig figs)

rule with sigs figs with a decimal/bar

if u add a bar/decimal the all the numbers before decimal count as significant (1000. has 4 sig figs while 1000 only has 1)

right and right rule

zeros to the right of the decimal and are also to the right of a sig fig are significant (2.50 has 3 sig figs while 0.025 has 2 sig figs)

place holder zeros

hold value of the number, are not significant (250 has 2 sig figs and 1 place holder 0)

what happens to precision when math operations occur

when calculations are preformed, error can be compounded. therefore the precision of the answer to a calculation is reliant upon the lest precise measurement used in the calculation (relates to why sig figs are important)

precision rule in adding and subtracting

amount of decimal places In final answer depends on the least number of decimal places of both numbers in the original equation

precision rule in multiplying and dividing

amount of sig figs depends on the least number of sig figs found of both numbers in original equation

scientific notation

a way of writing really big numbers in a more manageable form

rules of sci not

-can only have one digit to the left of the decimal (1.34)
-only sig figs are included in the mantissa
-number of power of 10 relates to how many times the decimal was moved

positive exponent in sci not

number is large so decimal will move to the left

neg exponent in sci not

number is small so decimal will move to the right

mantissa

the numbers left the times 10 part (idk what this even means but that's how it was in the notes)

standard notation

just opposite sci not, a number how we would usually write it

measurement

a quantity that has both a number and a unit, determines amount

unit

used to express the size of a measurement

matter

anything that has mass and takes up space (people, objects, air/atoms, water), usually has mass and volume

not examples of matter

light heat energy

qualitative

data in the form of words, matter can be described like this

quantitative

data that is in numbers, matter can be described like this

SI units

systematic international units...standard unit of measurement for everyone

mass

a measure of the amount of matter in an object (g,mg,kg)

volume

the amount of space an object takes up (mL, L, qt)

density

amount of mass that occupies a volume, intensive property, low ____ will float, high ____ will sink

density equation

D=m/v

qualitatively compare density example

if a marble has a low density than it will float because it is less dense than the water. if a marble has a high density it will sink because it is more dense than water

why do measurements need units

to determine how big/small the measurement is and what kind (like is it liquid or length or weight or whatever)

You gals are smart and r gonna do so good

don't stress about this and if your up late go to bed cause sleep is good...bye have a good day mwah????

also jus one more thing

this is literally everything she gave us like everything from the chem pack sheet and notes we took in class so if we do bad//the test is on random shit imma throw hands but she told me she usually curves tests so yay!