Question

3 The boiling points of pure HF, HCI, HBr and Hl are -20, -85, -66 and -34 °C, respectively. Identify the trends in bond polarity and dispersion forces along this series. (i) (ii) (iii) Use this information to assess the relative strengths of these two effects in this case (3 marks) Suggest a reason for the anomalous behaviour of HF. (3 marks) Calculate (a) the total number of atoms in a 3.2 cmsample of pure liquid HCl, (b) the number of moles of HCl in 1 L of the pure liquid. Note that the density of liquid HCl is 1.49 g cm. (7 marks)

Answer 1

eaed Bailing bnrt Comp OKDER DF -20 00 HF -S Bmd prlonla Kond prlanby AX CXeleeho ORDER DF -34 'C ИТ neya RDER DF Disperstm foscee induca dupisu- induud dupda inhacle

London foree Cdispernion fone) Atomic no C1>Ri >r Sincee no duspem fe Anomalaus behauion Reaarm nf Eraphimed Bnall bn F alem md hyh chonge dlenty Volmsample - 3 2 cm3 Vncu 3.2 Cm3 - 1 44 /cm neVolm dunply = 3-2 x0 140 9 4.7689 nc 4-168 O.13r6 mde 36-5 mdcul fnel nne, XN A no 23 6-136 x 6-022X10 P.86X1022 mdeal

106D Cm Vh IL= 100ml Vnax fnu anci 1.44 9 14909 1490 36.5 mle z 40 82