Chem 30A Units of Measurement 08 27 2014 Day 1 Notes Length volume mass temperature Metric system vs US System SI International System of Units Length meters Volume m3 Mass kilograms kg Temperature Kelvin K Time seconds s 3 significant concepts of measurement units scientific notation significant figures conversion ex of scientific notation 1 1 392 000 000 1 392 109 2 0 0000000003 3 10 10 characteristics of significant figures all non zero digits are significant interior zeros are significant trailing zeros after a decimal point are significant figures leading zeros are not significant figures zeroes at the end of a number without a decimal point are ambiguous Day 2 Notes Significant figures 20 ml of water 1 sig fig 20 0 ml 2 sig fig 20 00 ml 4 sig fig 150000 2 sig fig Scientific notation 1 5 105 500 1 sig fig 0 00040 2 sig fig 1 052 4 sig fig 1500 2 sig fig 1304 4 sig fig 0 010 2 sig fig 5 02 3 sig fig 89 665 5 sig fig 0 10 2 sig fig 45 01183 5 74 3 sig fig 0 823 3 sig fig 2 651 4 sig fig cut out the 3 and the 1 9 21 3 489 5 67 2 3 11 75793 rounded to 12 Take home problem 3 2215 1 67 2 3 8 Exact numbers conversion factor or formulas are NOT counted when doing sig figs measured by us Conversion problems 1 48 3 in feet 48 3 in 1 ft 12 in 4 025 feet 4 03 feet after rounding to 3 sig figs 2 67 2 in cm 67 2 in 2 54 cm 1 in 171 centimeters 3 120 grams ounces 120 g 1 lb 452 g 0 27 lb 0 27 lb 16 oz 1 lb 4 3 oz Must know Bolded chemical elements Metric to metric conversion Day 3 Notes Volume Liters L Mass Gram g Length Kilometer km 103 Meter m 100 Decimeter dm 10 1 Centimeter cm 10 2 Millimeter mm 10 3 Micrometer Um 10 6 Nanometer nm 10 9 Picometer pm 10 12 Ex 10 cm Um 10 cm 10000 Um 1 cm 10 000 Um 1 10 5 Um Ex 25 pm Um 25 10 6 000025 2 5 10 5 Um Ex 0 006 g mg 0 006 g 10 6 mg 1 g 6000 mg 6 10 3 mg Density mass volume how much mass in a given volume Mass is grams volume is Ml or grams cubed centimeter 1 ml is 1 cm 3 Dimensions 4 3 2 24 cubed units Density of gold 19 32 g mL kg m 3 19 32 g mL 1 kg 10 3 g 1000 mL 1 cubed liter 1 L 1 m 3 19 32 kg m 3 100 00 lb ft 3 g cm 3 100 lb ft 3 454 g 1 lb 1 ft 3 1728 in 3 1 in 16 387064 cm 3 1 6033 g cm 3 13 9 lb ft 3 oz in 3 13 9 lb ft 3 16 oz 1 lb 1 ft 3 1728 in 3 0 129 oz in 3 Take home Density of gold is 19 3 g cm 3 What is the mass of a a bar of gold in kg that measures 6 0 in by 4 0 in by 2 0 in Dimensions 6 4 2 48 cubed inches 19 3 g cm 3 1 kg 1000 g 16 387 cm 3 1 in 3 0 316 kg in 3 48 in 3 0 316 kg 1 in 3 15 kg Physical vs Chemical Changes 08 27 2014 Day 4 Notes Physical changes changing the composition reversible H2O s H2O l heat Chemical changes When something new is formed cannot be reversed CH4 O2 CO2 H2O forms a new product Physical or chemical change a Peeling potatoes Physical b Baking bread Chemical c Cooking eggs Chemical d Homogenizing milk e Distilling water Physical Physical f Burning toast Chemical g Vaporizing water Physical h Milk changes to cheese Chemical i Milk is heated Physical Matter is either pure substances or mixtures Pure substances or either compounds or elements Two types of mixtures homogeneous heterogeneous Mixtures mixing compounds and elements Compounds More than one type of element chemically combined in a specific ratio with other elements NaCl sodium chloride is a compound H2O water is a compound C6H2O6 glucose is a compound N2O CO NO CO2 NO2 N2O5 Ex 10 g NaCl 90 g H2O Salt water 10 g NaCl 100 g 100 10 NaCl solution Ex Heterogeneous solution Oil H2O How could you make a 20 NaCl solution 20 g NaCl 80 g H2O 100 g 20 g NaCl 100 g 100 20 4 08 27 2014