AAC Chemistry Unit 1

Accuracy

how close a measurement is to the true value

Precision

How close a group of measurements are to each other, "amount of times you can hit the same spot

Why do sig figs matter?

To have one common way of showing measurements amongst all scientists in the world

To be honest when reporting sig figs:

We control the amount of digits

An uncertainty

A digit that needs to be estimated at the end of a measurement, a guess

Record all digits in sig figs and:

The first uncertain digit

meniscus

Liquid curve, measurement at bottom of liquid curve

Use scientific notation if:

your CALCULATOR gives the answer to you in scientific notation

What digits are always significant?

nonzeros

When are zeros significant? (2 questions to ask in 1 rule, another rule as well)

The questions rule: If there's a decimal in the number AND is the zero after a nonzero.The sandwich rule: if sandwiched (no matter how many zeros) between 2 nonzeros

What are exact numbers?

Numbers you get by counting.

Do you have sig figs with exact numbers?

No. You can also answer that there are an infinite amount of sig figs

The coefficient of scientific notation is:

The number before the x (multiplication) that has a decimal

The coefficient in sci not. has to be:

Greater than or equal to 1, less than 10 (only a chemistry rule)

When à questions says to round to a certain amount of sig figs, the __ still has to have that amount of sig figs.

Answer

To add/subtract sig figs:

Mark the number with most specific place value THATS A SIG FIG, then choose the one that's least specific ex: 2.05 +3500, the 5 from 2.05 in the hundredths place is very specific, but the 5 in the hundreds place is less specific, so choose the hundreds place value to round the final answer to

Multiplication/ division

Choose which # in the equation has the least number of sig figs then make your answer have that many sig figs

Switching between +/- and x/division ...

Round in between/ halfway