Chem1330ClassNotesfor23August2017 (2).pdf

# Chem1330ClassNotesfor23August2017 (2).pdf - Ways of...

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Unformatted text preview: Ways of Expressing Concentrations of Solutions Molarity (M) M Z L of solutlon This concentration measure was deﬁned WV CMPK/ 4' games L! Lt Since volume is temperature—dependent, molarity can change with temperature. Mole Fraction (X) X z ., moles of A A total moles 1n solutlon Sometimes need the mole fraction of solvent, not solute — make sure you ﬁnd the quantity you need! Mass Percentage O : Mass A) OfA total mass of solution Parts per Million and Parts per Billion Parts per Millien (ppm) mass of A111 solution 106 pp total mass 0f solution Parts per Billien (ppb) b __ mass of A111 solutm x 109 pp total mass of solution X 100 Molality (m) kg of solvent Neither moles nor mass change with temperature, molality (unlike molarity) is not temperature-dependent. Calculating Molality What is the molaiity of a solution prepared by dissolving 32.0 g of CaCi2 in 271 g of water? Mei (:I‘Li/V/gliiy _._.. nmﬁi Cg 512/ ”Vi/L : M ##2##“ id got & b, ‘4 ‘ hit it)? Expressing Concentrations in Parts by Mass, Parts by Volume, and Mole Fraction PROBLEMS: (a) Find the concentration of calcium (in ppm) in a 3.50-g pill that contains 40.5 pg of Ca. «m of Ca: 4m A2,;— , 94 y (4 gh; WUSOPPHI ; 3%? my}? 0 000 0 3 (b) The label on a 0.750—L bottle of Italian chianti indicates “11.5% alcohol by volume.” How many liters of alcohol does the wine contain? (c) A sample of rubbing alcohol contains 142 g of lsopropyl alcohol (C3H7OH) and 58.0 g of water. What are the mole fractions of alcohol and water? Y: 71w fl" A 4/6411? m‘é/ ~ L: M32 QIJMHXL ml [50!)va ale lw/ 9 w 6%? “Ma! Cﬂﬁm": glﬁémc/ Mel 147/0 :5 “My? WC X 574:] z j 2,17;le " J lnterconverting Concentration Terms Hydrogen peroxide is a powerful oxidizing agent used in concentrated solution in rocket fuels and in dilute solution as a hair bleach. An aqueous solution H202 is 30.0% by mass and has a density of 1.11 g/mL. Calculate its (a) Molality 71/1 :2 36746175ngch1 left/11133 '3"? 35?» 02 WE WW] \$53615; W ‘ '7: ”70/ j * 300 [Mix M“ ) M. 0,382 ”Mast M 1 ’ C) Q! J19 W)” % (793W >< My :- Oﬁam/tw #133 [0620? 1 02 33:2. 'Mw/ W2” “Vi/L ”g“ 0; 04 arcs/é? ”25} tr: fCQQ/nk (b) Mole fraction of H 202 3] 1436/ Hﬂ’uzf 34303” W “Wizzéf H3032, w (93 8 X '32 W‘J’ W W x 96% 03 W3, W 3 33 33/ lgié/g [71% ”M [3* %’§>Zﬁul H2095 w 15/ HyLy/g (ﬁggiww/ [3+3 5367,7439/W Oil/3’?) (c) Molarlty @‘ﬁ‘ H»; 03 ,3 MM HEEL “V" L gésiaﬁw L. ‘5}03 ganﬂPéWCEXLdpngihmx 1 ML *’ - 6.0670! L‘ (% Mi? WQQML gfﬁmﬁm ...
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