In each case, decide if the change is a chemical or physical change. A cup of household bleach changes the color of your socks from red to pink Water vapor in your exhaled breath condenses in the air on a cold day Plants use carbon dioxide from the air to make sugar Chocolate melts when placed in the sun

A cup of household bleach changes the color of your socks from red to pink - chemical Water vapor in your exhaled breath condenses in the air on a cold day - physical Plants use carbon dioxide from the air to make sugar - chemical Chocolate melts when placed in the sun - physical

Which types of properties help you identify WHAT a substance is? It has a mass of 2 kg It is 3 cm long It has a volume of 2 L It has a temperature of 280 K It is clear/colorless It is a liquid at room temperature It boils at 100 degrees Celcius It has a density of 1 g/mL

UNITS OF MEASUREMENT Use SI units — based on the metric system Length Mass Time Temperature Meter, m Kilogram, kg Seconds, s Kelvin, K

Conversions Commonly Used Prefixes: kilo = 1000 of something ( 1km= 1000m, kg) deci =0.1 of something (10 dm = 1m) centi = 0.01 of something (100 cm = 1m) milli = 0.001 of something (103 mm = 1m) micro = 0.000001 (106 µm = 1m) nano = 0.000000001 (109 nm = 1m) pico = 0.000000000001 (1012 pm = 1m)

Temperature Scales Fahrenheit Celsius Kelvin 32 ˚F 212 ˚F 180˚F 100 ˚C Boiling point of water 32 ˚F 212 ˚F 180˚F 100 ˚C 0 ˚C 100˚C 373 K 273 K 100 K Freezing point of water Notice that 1 kelvin degree = 1 degree Celsius

Temperature Scales 100 oF 38 oC 311 K oF oC K

Calculations Using Temperature Generally require temp’s in kelvins T (K) = t (˚C) + 273.15 Body temp = 37 ˚C + 273 = 310 K Liquid nitrogen = -196 ˚C + 273 = 77 K

DENSITY Density is an INTENSIVE property of matter. does NOT depend on quantity of matter. temperature Contrast with EXTENSIVE depends on quantity of matter. mass and volume (separately). Brick Styrofoam

Significant Figures: Digits in a measurement having values that are known with certainty plus one digit having a value that is estimated.

Measurements that contain a greater number of significant figures are more precise than measurements that contain fewer significant figures. Always select an instrument that gives you the most significant figures. Only report as many sig figs as that instrument allows.

The Rules

All numbers 1-9 are significant. Zeros are sometimes significant, here's how you can tell: If a decimal point is present, starts on the Pacific side, move across until you get to a 1-9 digit, and start counting to the end If a decimal point is absent, start on the Atlantic side, move across until you get to a 1-9 digit, and start counting to the end 1.100 has 4 sig figs, 0.00540 has 3, 40.01 has 4 1005 contains 4 sig. Figs., 23,000 has 2, 1,045,090 has 6

When multiplying or dividing measurements: round the answer to the same number of digits as the measurement having the fewest number of significant figures. When adding or subtracting measurements: round the answer to the same number of decimal places as the measurement having the fewest number of decimal places.

123456.7890 Identify the LEAST PRECISE measurement. Higher precision 123456.7890 Lower precision Identify the LEAST PRECISE measurement. Identify the MOST PRECISE digit (place) within that measurement. Round the answer to this digit (place).

Scientific Notation 10000000000000000000000 0.00000000000000000000000000001 There has to be a better way to write those numbers Rules for scientific notation 1) Write only the sig figs. Express the number starting with the one’s place followed by any decimal digits, times a power of 10. 2)To express a large number, count the number of decimal places needed to move to the one’s place, and make that number the exponent of ten. 3) To express a very small number, count the number of decimal places needed to move to the one’s place, and make that number the NEGATIVE exponent of ten. 4) You can always check it by writing out the expanded ten, and multiply it by the measured number.

Scientific Notation Examples: 0.0000000000000000000000000000000010 94140000000000000000000000000000000 = 9.414 x 1035