DAY 14 DAY 14 – Sig figs / Scientific Notation Day 15 - Density LAB Day 16 – Measurement / sig fig quiz

Density Lab Materials; – Cork stopper, Rubber stopper, Nut and bolt – Graduated cylinder, water Formula: D=M/V Data Table: MASSVOLUMEDENSITY Final (mL)Initial (mL)Volume Cork Stopper Rubber Stopper Nut & Bolt

Scientific Notation What's the goal of Scientific Notation? – Condense the number that is written Example: What would you rather write – Or – 4.56 x

Rules of Scientific Notation It’s all about the decimal point! And power of 10! Example:645,000 1 st … move the decimal point so one # is to the left of it nd … place “x 10” to the right x 10 3 rd … count the number of spaces you moved the decimal point X 10 5 Almost Done!

X 10 5 Now get rid of the zeros 6.45 X 10 5 Rules: #1..moving the decimal point to the left… the exponent gets bigger #2… moving the decimal point to the right… the exponent gets smaller 64.5 X 10… what's the exponent 6.45 X 10 4

Adding Exponents Rules: 1 st … exponents need to be the same. Move the decimal point until the two numbers have the same exponent 2 nd … add OR subtract the numbers… not the exponents. Example: Add the following #s…Follow the Rules 6.45 x x 10 4 Answer: 6.76 x 10 5

Convert to Scientific Notation Pretest 134,000 5,

Practice problems pg 32 Addition and Subtraction Every problem

Pretest Multiply (2 x 10 3 ) x (3 x 10 2 ) Divide (9 x 10 8 ) ÷ (3 x )

Multiplying / Dividing Multiplying Rules: – 1 st … multiply the numbers – 2 nd … add the exponents Dividing Rules – 1 st … divide the numbers – 2 nd … subtract the exponents

Practice Problems pg 33 Multiply (2 x 10 3 ) x (3 x 10 2 ) = Divide (9 x 10 8 ) ÷ (3 x ) =

Conversions Rules: 1 st … write down what you know 2 nd … write down what you want to know 3 rd … what conversion factor are you going to use to get there? Convert 48km to meters (factor: 1km=1000meters) =______m or 48000

Types of Measurements Precise vs. Accurate

Percent Error The Accepted value is a known value Error = Accepted - Measured

% error example The accepted density for copper is 8.96g/mL. Calculate the percent error for each of these measurements g/mL 8.92 g/mL 9.00 g/mL 8.98 g/mL 1.11%.45%.22%

Significant Figures or Sig Figs Tells the how precise the measurement is Example: Which is more precise?  3.5 or 3.52g

Rules for Sig Figs – pg Non-zero umbers are always significant 2.Zeros between non-zero numbers are always significant 3.All final zeros to the right of the decimal place are significant. 4.Zeros that act as placeholders are NOT significant. Convert quantities to scientific notation to remove the placeholders. 5.Counting numbers and defined constants have an infinite number of significant figures.

Examples – use your rules Which numbers are significant?  72.3  60.5  6.20   4320  Help yourself out – convert to Scientific Notation

Rounding Numbers – pg 40 1.If the digit to the immediate right of the last sig fig is less than five, do not change the last sig fig. 2.If the digit to the immediate right of the last sig fig is greater than five, round up the last sig fig 3.If the digit to the immediate right of the last sig fig is equal to five and is followed by a nonzero digit, round up the last sig fig. 4.If the digit to the immediate right of the last sig fig is equal to five and is not followed by a nonzero digit, look at the last sig fig. if it is an odd digit, round it up. If it is an even digit, do not round up

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