Which of the following is a pure substance? Sweat Beef stew Coffee Apple juice Ice Answer: E

Your Turn! Coffee is a homogeneous mixture. When you add sugar to it and the sugar dissolves… the coffee becomes a heterogeneous mixture. the coffee is still a homogeneous mixture. the coffee, which used to be a pure compound, is no longer a pure compound. the coffee, which used to be an element, is no longer an element. the sugar reacts with water to form a new compound. Answer: B

Which of the following is a heterogeneous mixture? Seawater Chicken soup Coffee Hydrogen peroxide Ice Answer: B

Your Turn! Which one of the following represents a physical change? when treated with bleach, some dyed fabrics change color grape juice left in an open unrefrigerated container turns sour when heated strongly, sugar turns dark brown D. in cold weather, water condenses on the inside surface of single pane windows E. when ignited with a match in open air, paper burns Answer: D

Which of the following represents a chemical change? Freezing water to make ice cubes Dry ice evaporating at room temperature Toasting a piece of bread Dissolving sugar in hot coffee Crushing an aluminum can Answer: C

Which of the following is a chemical property? Squeezing oranges to make orange juice Melting butter for popcorn Separating sand from gravel Hydrogen peroxide decomposing to water and oxygen Ozone as a gas at room temperature Answer: D

Your Turn! Which of the following is an extensive property? Density Melting point Color Temperature E. Mass Answer: E 7

It is a solid at 25 °C. It has a density of 1.38 g/cm3. Which of the following would NOT be considered an intensive property describing an unknown sample? It is a solid at 25 °C. It has a density of 1.38 g/cm3. It melts at 62.0 ° C. It has a volume of 0.52 cm3. It is shiny. Answer: D

Which of the following is NOT a base unit? Meter Kilogram Liter Kelvin Second Answer: C

Convert 40.00 °C into K and °F Find the equation that relates the given quantity to the quantity you want to find Given: Find: Equation: 40.00 °C K K = °C + 273.15 Because the equation is solved for the quantity you want to find, substitute and compute K = °C + 273.15 K = 40.00 + 273.15 K = 313.15 K Find the equation that relates the given quantity to the quantity you want to find Given: Find: Equation: 40.00 °C °F Solve the equation for the quantity you want to find Substitute and compute

Temperatures in Death Valley can rise above 120 ° F Temperatures in Death Valley can rise above 120 ° F. What is this temperature in Kelvin? 393 K –153 K 322 K 234 K Answer: C

Rules for Significant Figures All non-zero numbers are significant. e.g., 3.456 has 4 sig. figs. Zeros between non-zero numbers are significant. e.g., 20,089 or 2.0089 × 104 has 5 sig. figs Trailing zeros always count as significant if number has decimal point e.g., 500. or 5.00 × 102 has 3 sig. figs 12

Rules for Significant Figures Final zeros on number without decimal point are NOT significant e.g., 104,956,000 or 1.04956 × 108 has 6 sig. figs. Final zeros to right of decimal point are significant e.g., 3.00 has 3 sig. figs. Leading zeros, to left of first nonzero digit, are never counted as significant e.g., 0.00012 or 1.2 × 10–4 has 2 sig. figs.

Learning Check How many significant figures does each of the following numbers have? Scientific Notation # of Sig. Figs. 413.97 0.0006 5.120063 161,000 3600. 4.1397 × 102 5 6 × 10–4 1 5.120063 7 1.61 × 105 3 3.600 × 103 4

Your Turn! How many significant figures are in 19.0000? 2 3 4 5 6 Answer: E

Your Turn! How many significant figures are in 0.0005650850? 7 8 9 10 11 Could be rewritten as 5.650850  10-4 Answer: A

Which of the following numbers has four significant figures? 0.003 0.7180 0.10251 0.508 Answer: B

The data is both accurate and precise. A student measures the mass of a penny four times and records the following data. What can be said about the data if the actual mass of the penny is 2.4987 g? Trial Number Mass, g 1 2.5104 2 2.5106 3 2.5102 4 2.5109 The data is both accurate and precise. The data is neither accurate nor precise. The data is accurate, but not precise. The data is not accurate, but it is precise. Answer: D

Learning Check Round each of the following to three significant figures. Use scientific notation where needed. 37.459 5431978 132.7789003 0.00087564 7.665 37.5 or 3.75 × 101 5.43 × 106 133 or 1.33 × 102 8.77 × 10–4 7.66

Your Turn! Round 0.00564458 to four significant figures and express using scientific notation. 5.64  10-2 5.000  10-3 5.645  10-4 0.56446 5.645  10-3 Answer: E

Significant Figures in Calculations Multiplication and Division Number of significant figures in answer = number of significant figures in least precise measurement e.g., 10.54 × 31.4 × 16.987 4 sig. figs. × 3 sig. figs. × 5 sig. figs. = 3 sig. figs. e.g., 5.896 ÷ 0.008 4 sig. figs. ÷ 1 sig. fig. = 1 sig. fig. = 5620 = 5.62×103 = 700 = 7×102

Your Turn! Give the value of the following calculation to the correct number of significant figures. 1.21213 1.212 1.212132774 1.2 1 Answer: D

Significant Figures in Calculations Addition and Subtraction Answer has same number of decimal places as quantity with fewest number of decimal places. e.g., 12.9753 319.5 + 4.398 4 decimal places 1 decimal place 3 decimal places 336.9 397 – 273.15 0 decimal places 2 decimal places 0 decimal place 124

Learning Check For each calculation, give the answer to the correct number of significant figures. 10.0 g + 1.03 g + 0.243 g = 19.556 °C – 19.552 °C = 327.5 m × 4.52 m = 15.985 g ÷ 24.12 mL = 11.3 g or 1.13 × 101 g 0.004 °C or 4 × 10–3 °C 1.48 × 103 m 0.6627 g/mL or 6.627 × 10–1 g/mL

Your Turn! When the expression, 412.272 + 0.00031 – 1.00797 + 0.000024 + 12.8 is evaluated, the result should be expressed as: 424.06 424.064364 424.1 424.064 424 Answer: C

Your Turn! When the expression, 152.6736 - 0.0028 – 125.00797 + 56.795 + 12.853 is evaluated, the result should be expressed to the: tenths place hundredths place thousandths place ten-thousandths place hundred-thousandths place Answer: C

Learning Check For the following calculation, give the answer to the correct number of significant figures. 1. 2. = 2 × 10–4 m/s2 = 0.0087 cm3/s

Exact Numbers Exact numbers have an unlimited number of significant figures. A number whose value is known with complete certainty is exact Exact counting of discrete objects - 3.00… atoms Integral numbers that are part of an equation eg. radius = diameter/2.0000… Defined quantities (100.0000… cm = 1.000… m) Some conversion factors are defined quantities, while others are not. In the instances in this slide, the numbers are exact and therefore have an unlimited number of significant figures.

Your Turn! 36.00 has four sig. figs. The conversion is exact. Express the answer to the following with the correct number of significant figures: 3 ft. 3.0 ft 3.00 ft. 3.000 ft. 3.00000 ft. 36.00 has four sig. figs. The conversion is exact. So the answer has four sig. figs. Answer: D

Your Turn! For the following calculation, give the answer to the correct number of significant figures. 179 cm2 1.18 cm 151.2 cm 151 cm 178.843 cm2 Answer: D

Calibration and Measurement Read the water level with the correct number of significant figures. Read the length of the metal bar with the correct number of significant figures. Ans. _____________ A) 5 mL B) 5.3 mL C) 5.32 mL D) 5.320 mL E) 5.3200 mL A) 20 cm B) 15 cm C) 15.0 cm D) 15.00 cm E) 15.000 cm Read the temperature with the correct number of significant figures. A) 87°C B) 87.2°C C) 87.20°C D) 87.200°C E) 87.2000°C 5.3; 15.00; 87.20; 15.0 Read the length of the metal bar with the correct number of significant figures.

Perform the Following Calculations to the Correct Number of Significant Figures

Perform the Following Calculations to the Correct Number of Significant Figures

Calculate the following with the correct number of significant figures. 2 1.4 2.2 1.36 2.23 Answer: C

Using Dimensional Analysis Example: Convert 0.097 m to mm. Relationship is 1 mm = 1 × 10–3 m Can make two conversion factors Since going from m to mm use one on left. = 97 cm

Learning Check Example: Convert 3.5 m3 to cm3. Start with basic equality 1 cm = 0.01 m Now cube both sides Units and numbers (1 cm)3 = (0.01 m)3 1 cm3 = 1 × 10–6 m3 Can make two conversion factors or 3.5 × 106 cm3

Your Turn! The Honda Insight hybrid electric car has a gas mileage rating of 56 miles to the gallon. What is this rating expressed in units of kilometers per liter? 1 gal = 3.784 L 1 mile = 1.609 km 1.3 × 102 km L–1 24 km L–1 15 km L–1 3.4 × 102 km L–1 9.2 km L–1 Answer: B

Your Turn! The volume of a basketball is 433.5 in3. Convert this to mm3. 1.101  10-2 mm3 7.104  106 mm3 7.104  104 mm3 1.101  104 mm3 1.101  106 mm3 Answer: B

What is the density of a solution that has a mass of 13 What is the density of a solution that has a mass of 13.5 g and a volume of 15.8 mL? 1.17 g/mL 0.213 g/mL 4.69 g/mL 0.854 g/mL Answer: D

Learning Check 19.3 g/cm3 Another student has a piece of gold with a A student weighs a piece of gold that has a volume of 11.02 cm3 of gold. She finds the mass to be 212 g. What is the density of gold? 19.3 g/cm3 Another student has a piece of gold with a volume of 1.00 cm3. What does it weigh? 19.3 g What if it were 2.00 cm3 in volume? 38.6 g

Which of the following has the largest density? A material that has a mass of 10.0 g and a volume of 2.00 L A material that has a mass of 5.00 g and a volume of 10.0 cm3 A material that sinks in ethanol but floats on water Answer: C

Decide if a ring with a mass of 3. 15 g that displaces 0 Decide if a ring with a mass of 3.15 g that displaces 0.233 cm3 of water is platinum Write down the given quantities and the quantity you want to find Given: Find: Equation: mass = 3.15 g volume = 0.233 cm3 density, g/cm3 Find the equation that relates the given quantity to the quantity you want to find Solve the equation for the quantity you want to find, check the units are correct, then substitute and compute Compare to accepted value of the intensive property Density of platinum = 21.4 g/cm3 therefore not platinum

Learning Check 1. Glass has a density of 2.2 g/cm3. What is the volume occupied by 35 g of glass? 2. What is the mass of 400. cm3 of glass? 16. g 8.8  102 cm3

Your Turn! Titanium is a metal used to make artificial joints. It has a density of 4.54 g/cm3. What volume will a titanium hip joint occupy if its mass is 205 g? 9.31 × 102 cm3 B. 4.51 × 101 cm3 C. 2.21 × 10–2 cm3 D. 1.07 × 10–3 cm3 E. 2.20 × 10–1 cm3 Answer: B

Your Turn! A sample of zinc metal (density = 7.14 g cm–3) was submerged in a graduated cylinder containing water. The water level rose from 162.5 cm3 to 186.0 cm3 when the sample was submerged. How many grams did the sample weigh? 1.16 × 103 g 1.33 × 103 g 23.5 g D. 1.68 × 102 g E. 3.29 g Answer: D