Quantitative Properties For Matter 08/27/15

Reminders Quiz Monday You will use this information for tomorrow’s performance-based density lab

Agenda Define density How to measure Significant figures Scientific notation Accuracy vs precision *metric system*

Wrap-Up: Density Formula? Definition?

Wrap-Up: Density

Wrap-Up: Density

Agenda Define density How to measure Significant figures Scientific notation Accuracy vs precision *metric system*

How do you measure? We want the best measurement possible. Electronic scale  use all the digits given You read yourself  use what’s given + estimated digit Glassware such as graduated cylinder, beaker, etc Measuring devices such as rulers, meter sticks, etc

Estimated digit

Estimated digit

Estimated digit

Agenda Define density How to measure Significant figures Scientific notation Accuracy vs precision *metric system*

Significant figures – the “important” numbers Abbreviated as “sig figs” When should you round the final answer?

Significant figures – the “important” numbers The # of digits your final answer contains should be the same amount as the given with the lowest # of digits 5.5, 4.55, 3.256  5.5, 4, 3.256  Only as strong as your weakest link

Do you know your rounding rules? 0-4 rounds….. 5-9 rounds….

Sig figs – rules! There are rules for which numbers are significant (not all #s are important!) Easiest way to remember: the Pacific/Atlantic rule

PA rule – cross out all zeros depending on decimal

Sig figs - practice What is the density of an object with a mass of 12.0 g and a volume of 3 mL? What is the density of an object with a mass of 12.0 g and a volume of 6.0 mL? What is the density of an object with a mass of 10.0 g and a volume of 0.50 mL? What is the density of an object with a mass of 0.5 g and a volume of 0.05 mL? What is the density of an object with a mass of 0.100 g and a volume of 50.0 mL? What is the area of an object with a length of 50 cm and a width of 10 cm?

Agenda Define density How to measure Significant figures Scientific notation Accuracy vs precision *metric system*

Scientific notation #.# x 10# Use exponents to replace digits Start at decimal and move either forward or backward to get this formula: #.# x 10#

#.# x 10# # the decimal is always moved to after this digit # the number of these digits depends on how many sig figs you want # this represents how many times you moved the decimal over If you moved the decimal to the left, the digit should be negative (-) If you moved the decimal to the right, the digit should be positive (+)

Scientific notation examples Convert 3,000 to scientific notation using 2 sig figs Convert 3050 to scientific notation using 2 sig figs Convert 3040 to scientific notation using 2 sig figs Convert 0.000045 to scientific notation using 2 sig figs

Scientific notation examples Convert 3.45 x 102 to the decimal form using 2 sig figs Convert 8.565 x 10-3 to the decimal form using 3 sig figs

Agenda Define density How to measure Significant figures Scientific notation Accuracy vs precision *metric system*

Accuracy vs Precision Accuracy – how close your answer is to the true/accepted value (the answer) Precision – how close your answers are together

Accepted value: 5.75 A B C 5.55 6.96 4.32 5.65 5.75 1.63 5.21 3.23

Agenda Define density How to measure Significant figures Scientific notation Accuracy vs precision *metric system*

Metric System – largest to smallest Kilo_________ Hecta ________ Deca ________ (Base) ________ Deci ________ Centi ________ Mili ________

Metric System – largest to smallest Kilo_________ Hecta ________ Deca ________ (Base) ________ Deci ________ Centi ________ Mili ________ King Henry Died By Drinking Chocolate Milk