Question

Chame nsead tu age 06-17 Experiment 8: Molar Mass of a Volatile Liquid Purpose To determine the molar mass of a pure substance we need to find out (a) the number of moles in a given sample, and (b) the mass of the same sample. Molar mass is then: mass divided by moles Introduction Using the ideal gas equation, PV= nRT, we can determine the number of moles (n) of gas or vapor under measured conditions of pressure (P), volume (V), and temperature (T). The gas constant (R) is equal to 0.0821 L-atm/(mol-K), when the units of measurement are liters, atmospheres, moles, and Kelvin, respectively. In this lab we will follow a procedure to determine the mass of a vapor sample. Given our measurements of moles and mass, the molar mass is: M = m/n where M is the molar mass in units of g/mol, m is the mass in units of grams (g), and n is the number of moles (mol)-in other words; mass divided by moles. Procedure Just one Gather the apparatus: round-bottomed flask, stopper consisting of two pieces of aluminum foil, cork ring to support the flask (while weighing), top pan balance, 500-mL beaker (large enough for the round-bottomed flask to fit inside), boiling chips, thermometer, hot plate. Weigh the round-bottomed flask and record the result. Use the cork ring to letthe uarer sare un hr Sm support the flask on the balance. Pour 5 mL of unknown liquid into the round-bottomed flask Can the flask using the aluminum foil, and make a single hole in the cap using a 4 pin. C00m 20o Add about 150 mL of water to the 500-mt. beaker. vonso warr Add a few boiling chips to the beaker. Attach a utility clamp to the flask. Place the flask into the beaker and attach the clamp to a ring-stand. The round-bottom flask should be mostly below the level of the water in the beaker. If not, add morewater. Place the beaker on the hot plate and boil the water gently. Measure the temperature of the boiling water using a thermometer. 6 9. The unknown liquid will evaporate, and excess vapor will escape from the flask 10. After all the liquid has disappeared, continue to boil the water for 5 minutes. Molar Mass of a Volatile Liquid Experiment 8: ESP page 65 Trial 2 Trial 1 Results-show all calculations and units Unknown liquid units amount units amount 3 CS ML number: Mass of flask Mass of flask+ condensed vapor 138.2089 Temperature of water bath to Barometric pressure (original units given by the barometer) Pressure of vapor in atmospheres show calculation: 29.76 24.42at Temperature of vapor in Kelvin show calculation: CtA31r keluins 100.3C Mass of vapor show calculation: Mass of flask+ water (filled to the top of the flask) Mass of water Volume of flask showcaleuletion ho ralcdatun Q335 mL Just wnte he numy Experiment 8: Molar Mass of a Volatile Liquid derstu RT MW page 66 mes Verre Moles of vapor hepu R-T show calculation: RT massx Molar mass of unknown volatile liquid show calculation: page 67 Post-Laboratory Questions 1. Give the molecular formula for: A gas consisting of single atoms A gas consisting of molecules containing 4 or more atoms A gas consisting of molecules containing 3 atoms A diatomic gas 2. What is the difference between a gas and a vapor? 3. Calculate the root-mean-square speed of O, gas molecules at 120°C Consider the following reaction: 4NH,(g) +502(g) If 25 L of O2 are reacted with excess ammonia at a temperature of 22°C and a pressure of 1.1 atm, calculate the volume in liters of the NO produced. 4 4NO(g) + 6H20(g) A mixture of gases contains 0.55 mol 02, 0.14 mol N2, and 0.10 mol Ar. The total pressure is 3.2 atm. Calculate the partial pressures of the gases 5. Molar Mass of a Volatile Liquid Experiment 8: page 68 6. A 12 L vessel contains 16.5 g of a gas at 1.00 atm and 25.0°C. Calculate the molar mass of the gas.

Answer 1

All the answers are related to ideal gas equation. The detailed answer is in the images attached.
5)Given: mo,-0.55mol, MAr- 0.10mot, Ptal 3.2atm. to caleulate putial presses of the gas a.7077atm O.55 0.5540.1 0.84615 not MAT PAr: PIrtal X XAY = 0.49231atm A O.1 0.15384 O.65 16.5, P- latm, T- 25C -298k the gs c Given: To calculati the melar mas of V2 12L, m PV: nRT pV-MRT 0.0821 12 = 16.5x3t4 X Q98 . 9JK m 0.0&2J M16.5X83HX298 O.0821 3406.6615 12 33.64.051mot 5 meles 9gives 4 1. 1354 mles t o ses 4 meles ot NO 2meles NO x 4X11354 0.90832 moles 5 V: 0.10832x0,0821X215 19.99 20L 1.1

Experiment No. Date Name of the Experiment Page No 1 Moleculas X A pas cencidtg f dinge Aaiatomic atom: x gas coneiatug f Jascenialing of 3atoms A Xwhere nis the no 4 oi MoRe atoms atoms ingle safined thesmodyeamice 2 A 4as is a substanc fhat has truperatuse uhestasa vapor séfere to at ketmn a sthbatane &tatu at hoom tempesateure, naraly of & phases that is a mnictuse gasennskliguuid phase Root meansauiase im's sped 3RT M cOnstant g.3 kMo RE empesatuse Ro'c M2 Meleculas mass (I20 t232)k 393k 3X8.314X 313 32Ylo3 9R08 206 306,3189 Xlo3 ms= 32 1-5 O 13a.2913ms- 50 25L,Vitg To caleulate the Velumi in ihes of No rduad Ne can de this by idial pas eauauon T da%e2ata33= 215k, p.Llata excess P Y =NRT alx25-nxo.08 21x295 Yash S(SLEXIZBO'O Te 1354 motes 24, 2195 D.og