Question

10. (14 pts) For the compounds below: a. Identify the strongest intermolecular force present in each molecule. b. Arrange the following molecules in order of lowest vapor pressure to highest vapor pressure. c. Briefly justify your answer to part b using your knowledge of intermolecular forces. Molecule * HH * Strongest Intermolecular Force: Lowest vapor pressure: < < Highest vapor pressure 11.(12 pts) Ethanol (CH-OH, FW-46.08 g/mol) melts at -114 °C and boils at 78 °C. How much heat is required to convert 42.0 g of ethanol at 23 °C to the vapor phase at 78 °C? C C H OH(s) = 0.97 J/gK C. C-HOH (O) = 2.3 J/g.K C, C H OH (g) = 1.6 J/g.K AH ap 38.56 kJ/mol AHA = 5.02 kJ/mol

Answer 1

force (11) The Present strongest in each intermolecular molecule. 'c-o-Nat - Ionic Force. TCH?CHE CH3 van der I waal force is H₂C-CH₂-6-oth .. - - A Hydrogen 1 bonding. (D) Hz C-CH₂ St, CH₂ dipole - dipole forces. I (b) order of lowest vapour pressure .. to highest vapar pressure. huwest 'V.P) B < DLC <A CHighest V.P). (C) Stronger the Intermolecular forees of attraction among the molecule, more energy (in form of heat) will require to seperate them by lis Cabreaking I overcoming the forees.

Hence, more temperature is required to seperate them and convert them into gases I vapour state, so, Stronger the intermolecular forces, higher will be the boiling point The order of inter molecular forces Strength van-der - dipole - H-bonding 2 Imic. waal dipole (11) In this process, we need to consider two heat - q ,= heat ethanol require to warm ( 2961 to 78°€3516) liquid ✓ q = mass of (m) x Cg (C2 ts OH] (1) * (T2-T;) 1. ethanol → 9, = 42 8 * 2.3 In * 55 k = 1313 296k) to 23°C liquid hom ② ✓ V2=nAitvap = 429 x 38.56 - mo) 46.08 g where - q2 = 35.146 kJ. 42 n=number of moles = given weight = - Molecular weight 46108 .. Heat require to convert 42 g at 23°C to 78°C =qitu, = 5.313 + 35.146 Scanned with CamScanner - - q = 40.46 kJ Answer