June 2024 Flashcards
1.2. State the number of full 3d orbitals in an ion of Zn 2+. (1)
5
1.4. State why zinc is a good conductor of electricity. (1)
delocalised electrons are free to move (and carry a current)
2.4. State why the student used a conical flask rather than a beaker for the titration (1)
less chance of losing solution on swirling (of conical flask)
3.3. What is the shape of Boron Trifluoride (BF3)?
Explain why the BF3 molecule is non-polar, although a B–F bond is polar. (3)
(1) trigonal planar
(2) BF3 is symmetrical or BF3 is trigonal planar
(3) so dipoles cancel out
4.4. Suggest why a copper calorimeter is used rather than a glass beaker. (1)
copper is a good / better conductor (of heat)
4.5. Give 1 reason, other than heat loss, why the value obtained in the previous Q (no context needed) is different from the value given in the data book. (1)
incomplete combustion
5.2. In terms of structure and bonding, explain why magnesium has a higher melting point than sodium. (2)
(1) Mg2+/magnesium ion has higher charge (than Na+) or
Mg2+ ions smaller (than Na+ ions) or Mg2+ has greater charge density (than Na+) or Mg has more delocalised electrons
(2) stronger (electrostatic) attraction between cations / Mg2+ ions and delocalised electrons
5.3. In terms of structure and bonding, explain why phosphorus has a higher melting point than chlorine. (2)
(1) phosphorus molecule is bigger than Chlorine molecule or P4 is bigger than Cl2
or more electrons in phosphorus molecule
(2) so more / stronger van der Waals’ forces between molecules (to be broken or overcome)
5.8. Solid sodium bromide reacts with conc. sulfuric acid in a redox reaction. State 1 observation in this reaction. (1)
brown fumes or orange fumes
6.5. State, in terms of electrons, the meaning of a reducing agent. (1)
(reducing agent is an) electron donor
