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Lab 1 Molecular Mass of a Volatile Liquid

Lab 1 Molecular Mass of a Volatile Liquid - 25’ Section 0...

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Unformatted text preview: @ 25’ Section 0 0 £2 . EXPERIMENT 1 , MOLECULAR MASS OF A VOLATILE LIQUID" PRE-LABORATORY QUESTIONS The following preparatory questions should be answered before coming to lab. They are intended to introduce you to several ideas that are important to aspects of the experiment. You must turn in your work to your instructor before you will be allowed to begin the experiment. IOOIOOIOCOOOOCOIO.II...C...0....O....IIOIOCCCCCOQOIQOOOOCOOIIOIIOOOOIOI 1. Write the ideal and combined gas law equations. Which one of the two is relevant for this experiment? Boéiaz/OLW " V“? ’\ ChathS/S Law i, V d7 (we 3‘13; pa T) 0525 MA ' "fl ''''''''' My.“ M can W — WWW) \W.» ... , -. . » ~ WM *'*‘mass of ideal as . 2. The variable 11 can be wrltten as —___g— or g . Substitute molecular mass of ideal gas MM this quotient for n in the ideal gas equation and solve for the molecular mass. ChemiS 1 S—Academic Year 2010/201 1 1—1 ii‘- , .1; 3. Explain why it is necessary to remove the Erlenmeyer flask from the hot water bath at W the moment the volatile liquid disappears from the flask, rather than while there is still liquid in the flask, or minutes after the liquid has completely evaporated. To Q/V‘S‘Wfi, Wk Viv/’A‘m‘a $13!; egfia [141.23 M 919% g D ' W ' ~ $124,}; :vfiyeieimr" M‘gig fair WV” 62, Midweek £0,» mguwf Z , 6‘ § (0 4. Describe the experimental data which would be needed to determine the molecular mass of an unknown gas. .. Wigwam gig gg (was ofi {ma-er +n .em mat) (”LOSS 03* ugflaréy Gama; it? 3i$é¢éf”mi’é:‘§“fi\3 * Tmfygm-EAWQCTY S‘Cx wit {V iii 3 5% ie‘~«¥i‘*xi~%re ii‘ik’ikiB ' flrzfiwre (9‘) 5. A Chem. 1515 studeritnamed’KfLT'Cufley'isolated‘afiunknown” gas in aeglass bulb “Mr with a volume of 1.50 L at a temperature of 25 °C and pressure of 150 mm Hg. The gas weighed 194 mg. What is the molar mass of the gas? j;flqti:/‘Mmix fig : J‘Mg 7-. 26°+zwme : 149./§;«< ’ inQiS‘wfis ’0: ’90 Jerry {QQW : giq7QM;‘\/: Iz§0 L , ’ii; é‘W > ~ 81/ (3% L" i R' t O ME‘K 121’ (.194 yiimfiéfi (29%.:6X5 M”: 35—;- g. 01% WW; g) : /e,o7%m, Out of the following gases, which one closely matches the “unknown”? a) €sz b) C02 c) M d) co Chem15 15—-Academic Year 2010/201 1 1_2 Section 0 O 6 RESULTS Unknown Number #1 Trial #1 Mass of flask, foil cap, and rubber band Temperature of boiling water Mass of flask, foil cap, rubber band and condensed vapor Mass of condensed vapor Volume of flask Trial #2 Mass of flask, foil cap, and rubber band Mass of flask, foil cap, rubber band and condensed vapor Mass of condensed vapor Volume of flask SIGN-OUT: All equipment is put away, and the student bench is clean and dry. Chem] 5 l S—Academic Year 2010/20] 1 1—7 LIZ-c1 " 1 ,7 +0 FWV): .451) 44%;? . POST LABORATORY QUESTIONS 1. Use the ideal gas law to calculate the molecular mass of your unknown. Show your work below for both trials including unit conversions. Average the results. AW ; 3R1“ L“ ’J W”: (ole/4; X brl'g‘fifbw 22: K3 : $4: .242» ,5” V, ., H0 J M... Ac», . 4“, . p Tried 2.! my»? 3 C ' 7 V 7 7V ' (2 99”24'")L. 22:; 4—3 2. From its chemical formula and the periodic table, calculate the accepted value for the molecular mass of your unknown. UQVijgmfl = CH7)(_H7OH MM :(IzwtjmszJr lég/m, 4— (Loosiggflg 3693 : 4520“; We] c a. . 1M er 3 32%“ Aflf‘fifiw‘x 3. a. Calculate the % error of your experimental molecular mass. laccepted value - experimental valuel % error = ————-——————— x 100 acceptedvalue 71ml H 4/6 00% W /. 36 4;, ’4‘“, 0 l ’i l o I - OI 9 /9 % 5 " livaé‘fii gigging XIGQ .- Z ~i 72"“ / f: .. W; m .. W 7% "\2 UM {ml . b. Give a plausible reason why the expe mental molecular mass might be lower than the accepted value. fig mama We, ég: £25} M» 4m, iw and /e¥- $0444. of 6’ MIL (Ara-{tar val/MW" 11—0 e Sc aye c Give a plausible reason why the experimental molecular mass might be higher than the accepted value. £253”; ‘10“ #124142? [4,4, 4’”. “M5,; (55!: wait/+1422 rew‘ffig at?“ 12222??? 2 2%9/924442, @2307 4 A hydrogen gas t ermomet r is found to ha e a volum of 150 mL when placed in an ice- Water bath at 0°C. When the same thermometer is immersed in boiling liquid chlorine, the volume of hydrogen at the same pressure is found to be 131 mL. What is the temperature of the boiling point of chlorine? ChemISIS—Academic Year 2010/2011 1#8 Q ...
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