Chem 1406 Lecture 1 and 2 Exam 1

Exact vs Measured

Exact- a count

Measured- a number gotten from using measurements and have sig figs

Scientific Notation

Moving decimal to the left, positive

Moving decimal to the right, negative

Sig Fig rules

1-9 count

0’s in the middle counts

0’s that push numbers from the decimal don’t count

0’s after the number or decimal count

Multiplying and Dividing

The number with the least amount of sig figs will determine how many sig figs your answer should have

Adding and subtracting

Keep the smallest column in common, if they aren’t that is where the “chop” occurs

Prefixes

Big: kilo, grams

Small: centimeters, meter, mili

Conversions

Start with your given or measured numbers

Numbers have to match on the top from one side to the booth on the other side

Density

Mass is the amount of stuff

Volume is the space occupied

d=m/v or m=dxv or v=m/d

H2O liquid= 1g/mL

H2O ice= .9g/mL