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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 methanolcontaining 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.
 Fall '11
 CAMPBELL

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