11/ 15

Question

11/ 15
UCT ONLINE
HIGH SCHOOL
PHYSICAL SCIENCES
Question 3.2 (3 marks]
Use the table above and identify the substance that will have the lowest vapour
pressure. Explain your answer.
Question 3.3 [1 mark]
Write down the boiling point of NH3.
Question 3.4 [4 marks]
The boiling points of the Group 5 hydrides seem to increase as we go down the
group. Explain why NH, does not follow the general trend like the other Group 5
hydrides.
Question 3.5 [4 marks]
Explain why the boiling points of the Group 5 hydrides are higher than those of
corresponding Group 4 hydrides from periods 3 to 5, by referring to the type of
intermolecular forces present in these compounds and the energy involved.
Question 3.6
Table salt (NaCe) will dissolve in water (H,0) in a process called dissociation.
Question 3.6.1 [1 mark]
Name the type of intermolecular force present in the solution between table salt
(NaCe) and water (H,0) during this process of dissociation.
Question 3.6.2 (2 marks]
Do you think CH, will dissociate in water? Explain your answer.
TOTAL: 17
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GPT 3.5 · Answer

Question 3.2: The substance that will have the lowest vapor pressure is A since it has the highest boiling point, indicating that it is less volatile compared to the other substances.

Question 3.3: The boiling point of NH3 is -33.34°C.

Question 3.4: NH3 does not follow the general trend of increasing boiling points in Group 5 hydrides because it forms hydrogen bonds with water molecules due to its ability to donate a hydrogen atom, leading to stronger intermolecular forces compared to the other Group 5 hydrides.

Question 3.5: The boiling points of Group 5 hydrides are higher than those of corresponding Group 4 hydrides due to the presence of hydrogen bonding in the Group 5 hydrides, which requires more energy to break compared to the weaker van der Waals forces present in the Group 4 hydrides.

Question 3.6.1: The type of intermolecular force present in the solution between table salt (NaCl) and water (H2O) during dissociation is ion-dipole forces.

Question 3.6.2: CH4 will not dissociate in water because it is a nonpolar molecule and does not have the ability to form ion-dipole interactions with water molecules like ionic compounds.