Worksheet 1 Key - Chem 142 Autumn 2011 Name Group Activity 1 Significant Figures Units and Conversion Factors 1 A How many significant figures are

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Unformatted text preview: Chem 142, Autumn 2011 Name % Group Activity 1: Significant Figures, Units, and Conversion Factors 1. A. How many significant figures are in each of the following numbers? 5.40 3 3.97 x 10'5 3 30000 | 250. 7 3 1.4895 5 1.400 ‘+ 235.40 5 B. Complete the following calculations to the appropriate number of sig. figs.: 234.52 + 25.2 = 25%.”! 1420 x 320. = +5le lDs (6.274x103) x (1.56x10'2) = 101.1% xlo‘ -:— ‘17-‘l 529 + 1.30 = +01 3 ID2 = +01 430.-44.67= .3-‘353‘107' = 3%‘5 (1.343x102) + (1.5654x102) '= 23108 x I D” = zqo. $5 10f4 Chem 142, Autumn 2011 2. The average speed (um) of a collection of gaseous molecules is given by the following formula: ""3 M where T is the temperature of the sample,M is the molar mass of the gaseous compound, and R is a constant related to the distribution of the available kinetic energy over the molecules in the sample (R a 8.314 J mol‘1 K'l). What is urms for nitrogen gas (M = 28.02 g mol‘l) at 298.15 K? T 74mg =‘aVeI/aie 9,96% = 35.. M M: molav massCNz) l‘lfiDD'l x2.— = 291.014 3/m01 20f4 Chem 142, Autumn 2011 3. Methanol (methyl alcohol or wood alcohol) is a potential automotive fuel, either in pure form or mixed with gasoline. Some‘fleet vehicles, such as municipal buses, have been modified to burn methanol-containing fuels. These fuels are also used by some race cars. A particular automobile modified to use a mixture of 85.0% methanol and 15.0% gasoline by mass gets 25.5 mi/gal. The fuel has a density of 0.775 g/mL. How many kilograms of methanol does the automobile consume in a trip of 808 km? 1,061+ yal ‘ “4" ’3‘” - IE ‘601 km “300?” ‘ jallons le _ Im l’lwoyal 25.5w acme! armsLHZL lOOOML 07"!ij Haj 14.06156] gal _....—-———+-— K3 me I jal l/ ML. 10003 41M“ 51.9 [ca 0.15 Meihanol : Lr‘lllLi'SS W+hanol . i ' ,. ID '45 PM '93 Sig 9'69 7 Lloll I WOH 30f4 Chem 142, Autumn 2011 Potentially helpful information. Conversion factors: Length 1 m = 1.094 yd 1 mi = 5280 ft 1 ft = 12 in 1km=103m - 1mi=1760yd 1A=10'1°m 1 m = 102 cm (centimeters) 1 in = 2.54 cm (exact) 1 m = 103 mm (millimeters) Mass 1 kg = 2.205 lb 1 lb = 453.6 g ' 1 amu = 1.6605 x 10'27 kg 1 02 (ounce) = 28.35 g Volume 1 L = 1000 mL = 1.06 qt 1 ft3 = 28.32 L e 1 mL = 1cm3 = 0.03381 oz 1 gal = 3.785412 L = 4 qt Pressure 1 atm = 760. mmHg 1 torr = 1 mmHg 1 atm = 14.6959 Ila/in2 (psi) 1 atm = 101,325 Pa 1 Pa = 1 N/m2 1 bar = 100 kPa Energy 1 eV = 1.602 x 10'19 J 1 cal = 4.184 .l (exact) Force I 1 N = 0.22481lb Compound Units: ‘ Newton (N): 1N = 1kg.m/s2 Joule (J): 1] = 1N.m = kg.m2/s2 Metric prefixes: kilo (k) = 103 mega (M) = 106 giga (G) = 109 tera (T) = 1012 peta (P) = 1015 centi (c) = 10'2 micro (u) = 10'6 nano (n) = 10'9 pico (p) = 10'12 femto (f) = 10'15 Physical Constants: mass of electron 0.000549 amu mass of proton, 1.00728 amu mass of neutron ' 1.00867 amu ' Avogadro's Number (NA) 6.0221367 x 1023 speed of light 2.99792 x 108 m/s acceleration due to gravity 9.80665 m/s2 4of4 ...
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This note was uploaded on 01/18/2012 for the course CHEM 142A taught by Professor Campbell during the Fall '11 term at University of Washington.

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Worksheet 1 Key - Chem 142 Autumn 2011 Name Group Activity 1 Significant Figures Units and Conversion Factors 1 A How many significant figures are

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