Carmel (2017) Flashcards
1
Q
Tube of gas with air in it is compressed so that it has less volume. Why does pressure increase (KT). (2)
A
- Volume is reduced => spacing between particles becomes less but speed remains constant.
- Particles have less distance to travel between collisions and so the collision rate with the walls increases => force on the wall is greater => pressure is greater.
2
Q
Explain why Cl has higher 1st ionisation energy than Mg. (3)
A
- Cl is to the right of the periodic table => it has more protons in its nucleus.
- Same N.o. of electron shells however, Cl has a greater number of protons attracting valence shell.
- Due to greater force of attraction (core charge), more energy is required to remove an electron in the valence shell.
3
Q
Why is the S-Cl bond a polar covalent bond? What causes this polarity? (3)
A
- S and Cl atoms share the electron pair of the bond so they both have a stable 8 (octet rule).
- However, Cl atoms have more protons and will attract the bonding pair to a greater extent.
- Thus, bonding pair is pulled closer to the Cl, making it slightly more negative and making the Cl-S bond polar.
4
Q
Why can carbon form 3D structures like diamond but sulfur cannot? (3)
A
- Carbon has 4 valence electrons => can form 4 bonds.
- 4 bonds would repel each other according to VSEPR theory to produce a 3D tetrahedral structure.
- Sulfur only has 3 bonding pairs which would repel into a 2D planar structure
5
Q
Compound X is a strong electrolyte, Y is a weak electrolyte and Z is a non-electrolyte. Explain the differences between the compounds in terms of their degree of ionisation and give an example of each type of substance. (6)
A
- Substance X will be an ionic salt, made from an acid and a base or a strong acid or strong base. All fully dissociate in water. (E.g. NaCl)
- Y is a covalent substance but will partially dissociate in water. (E.g. CH3COOH)
- Z is a covalent substance and produces no ions in solution. (E.g. Kerosene)
