liquid and gas solid and Heat added () 5, (MC) Based on the figure above, the ph
ID: 555554 • Letter: L
Question
liquid and gas solid and Heat added () 5, (MC) Based on the figure above, the phase changes B C and D E are not associated with temperature increases because the heat energy is used up to (a) increase distances between molecules (b) break intramolecular bonds (c) rearrange atoms within molecules (d) increase the velocity of molecules (e) increase the density of the sample 6. (MC) Which one of the following substances will have hydrogen bonding as one of its 0 0 HCH (a) H-CH (b) HC CF (c) H H (d) H (eF 7, (MC) The volume of a sample of gas (2.49 g) was 752 mL at 1.98 atm and 62 The gas 1S (a) SO2 (b) SO3 (c) NH3 (d) NO2 (e) Ne 8. (MC) The value of AHo for the following reaction is -3351 kJ: 4 Al (s) + 3 O2 (g) 2 Al2O3 (s) The value of 1h" for Al-03 (s) is (a)-3351 (b) -1676 (c)-32.86 (d)-16.43 (e) +3351 kJ.Explanation / Answer
5) During the phase transition , the heat supplied is used up in breaking the attractive forces or intermolecular bonds between the molecules , hence no temperature rise is observed.
option B {should be inter molecular}
6) option D
CH3NH2 methylamine has H- bonds as it has H attached to N which are polar.
The others do not have H on F/O or N
7) let us calculate the molar mass of agas from the given data .
PV = (mass/ molar mass) Rt
P =1.98 atm
V= 752mL =0.752L
T = 62 C = 62+273 = 333K
and mass of sample = 2.49g
Thus molar mass = mass x RT/PV
= 2.49x 0.0821 x 333/ 1.98 x 0.752
= 45.72 g/mol
Thus the gas is NO2 with molar mass of 46g/mol
8)OPtion B
The reaction for formation of Al2O3 is
2AL(s) + 3/2O2(g) ------------> AL2O3(s)
this canbe obtained by dividing the givenequation with 2
Thus delta Hf = delta h of givenequation /2
= -3351/2
=-1675.5 kJ/mol
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