5 B. Percent Error your value accepted value Indicates accuracy of a measurementyour valueaccepted value
6 B. Percent Error % error = 2.90 % A student determines the density of a substance to be 1.40 g/mL. Find the % error if the accepted value of the density is 1.36 g/mL.% error = 2.90 %
7 C. Significant Figures Indicate precision of a measurement. Recording Sig FigsSig figs in a measurement include the known digits plus a final estimated digit
8 C. Significant Figures 2.35 cm Indicate precision of a measurement. Recording Sig FigsSig figs in a measurement include the known digits plus a final estimated digit2.35 cm
9 C. Significant Figures Count all numbers EXCEPT: Counting Sig Figs (Table 2-5, p.47)Count all numbers EXCEPT:Leading zeros (not significant)Trailing zeros without a decimal point -- 2,500 (not Significant)Zeros between numbers are significant
10 Counting Sig Fig Examples C. Significant FiguresCounting Sig Fig Examples3. 5,2803. 5,280
11 Counting Sig Fig Examples C. Significant FiguresCounting Sig Fig Examples4 sig figs3 sig figs3. 5,2803. 5,2803 sig figs2 sig figs
12 C. Significant Figures Calculating with Sig Figs Multiply/Divide – The # with the fewest sig figs determines the # of sig figs in the answer.
13 Multiplication and Division Rules Do the sumRound the answer to the least significant figure in the problem13.91g/cm3)(23.3cm3) = g4SF 3SF 3SF324g
14 C. Significant Figures Calculating with Sig Figs (con’t) Add/Subtract - The # with the lowest decimal value determines the place of the last sig fig in the answer.
15 Addition and Subtraction Rules Stack the numbers so that the decimal point is alignedDo the sumFigure out which number has least decimal place (least precise/decimal area least far out)Draw a line after the last number with the least decimal placeRound the digit by looking at the number that follows
17 C. Significant Figures Calculating with Sig Figs (con’t) Exact Numbers do not limit the # of sig figs in the answer.Counting numbers: 12 studentsExact conversions: 1 m = 100 cm“1” in any conversion: 1 in = 2.54 cm
18 Practice Problems - 0.84 g 18.06 g 5. (15.30 g) ÷ (6.4 mL) 4 SF 2 SF
19 D. Scientific Notation 65,000 kg 6.5 × 104 kg Converting into Sci. Notation:Move decimal until there’s 1 digit to its left. Places moved = exponent.Large # (>1) positive exponent Small # (<1) negative exponentOnly include sig figs.
20 Practice Problems D. Scientific Notation 7. 2,400,000 g 8. 0.00256 kg 9. 7 10-5 km 104 mm
21 Practice Problems D. Scientific Notation 2.4 106 g 7. 2,400,000 g kg9. 7 10-5 km 104 mm2.56 10-3 kgkm62,000 mm
22 D. Scientific Notation Type on your calculator: = 671.6049383 Calculating with Sci. Notation(5.44 × 107 g) ÷ (8.1 × 104 mol) =Type on your calculator:EXPEEEXPEEENTEREXE5.4478.1÷4== 670 g/mol= 6.7 × 102 g/mol
23 E. ProportionsDirect ProportionyxInverse Proportionyx
25 Quantity - number + unit A. Number vs. QuantityUNITS MATTER!!
26 B. SI Units Length l meter m Mass m kilogram kg Time t second s Temp T QuantitySymbolBase UnitAbbrev.LengthlmetermMassmkilogramkgTimetsecondsTempTkelvinKAmountnmolemol
27 B. SI Units Prefix Symbol Factor mega- M 106 kilo- k 103 BASE UNIT --- 100deci-d10-1centi-c10-2milli-m10-3micro-10-6nano-n10-9pico-p10-12
28 M V D = C. Derived Units 1 dm3 = 1 L 1 cm3 = 1 mL Density Combination of base units.Volume (m3 or cm3)length length length1 cm3 = 1 mL1 dm3 = 1 LDensity(kg/m3 or g/mL or g/cm3)mass per volumeD =MV
31 D. Density V = 825 cm3 D = 13.6 g/cm3 M = ? GIVEN: WORK: An object has a volume of 825 cm3 and a density of 13.6 g/cm3. Find its mass.GIVEN:V = 825 cm3D = 13.6 g/cm3M = ?WORK:
32 D. Density V = 825 cm3 M = DV D = 13.6 g/cm3 M = (13.6 g/cm3)(825cm3) An object has a volume of 825 cm3 and a density of 13.6 g/cm3. Find its mass.GIVEN:V = 825 cm3D = 13.6 g/cm3M = ?WORK:M = DVM = (13.6 g/cm3)(825cm3)M = 11,200 g
33 D. Density D = 0.87 g/mL V = ? M = 25 g GIVEN: WORK: A liquid has a density of 0.87 g/mL. What volume is occupied by 25 g of the liquid?GIVEN:D = 0.87 g/mLV = ?M = 25 gWORK:
34 D. Density D = 0.87 g/mL V = M V = ? M = 25 g V = 25 g 0.87 g/mL A liquid has a density of 0.87 g/mL. What volume is occupied by 25 g of the liquid?GIVEN:D = 0.87 g/mLV = ?M = 25 gWORK:V = MDV = g0.87 g/mLV = 29 mL