F321 jan 11 questions Flashcards
Why is the second ionisation energy of rubidium larger than the second ionisation energy of strontium? (2)
- 2nd IE of Rb involves removing electron from shell closer to nucleus
- Stronger nuclear attraction on (outermost electron) of Rb OR (outermost electron) of Rb experiences less shielding
Explain why a solution of copper(II) nitrate conducts electricity. (1)
ions can move
What is meant by the term electronegativity? (2)
The ability of an atom to attract electrons
in a covalent bond
State one use of calcium hydroxide in agriculture and suggest why the amount of calcium hydroxide used should not be excessive. (2)
- Used to neutralise acidic soils
2. Excess will result in soils becoming too alkaline (to sustain crop growth)
Suggest one other difference the student would observe between the reactions of water with calcium and of water with barium. (1)
Ba having a quicker rate OR more vigorous reaction
The student added bromine water to aqueous solutions of sodium chloride and sodium iodide in separate test-tubes. The student then added an organic solvent, cyclohexane, to each test-tube and these were shaken.
• State what colour you would see in the cyclohexane in each test-tube after shaking.
• Write ionic equations for any chemical reactions that take place.
• State and explain the trend in reactivity shown by these observations (6)
Colours:
1. (Add Br2 to NaCl,) (Cyclohexane layer) turns orange OR yellow
2. (Add Br2 to NaI,) (Cyclohexane layer) turns purple OR lilac OR violet OR pink OR mauve
Equation:
3. Br2 + 2I– -> I2 + 2Br–
Reactivity:
4. Reactivity decreases down the group OR Oxidising power decreases down the group
Explanations:
5. Chlorine will gain electron easiest OR form negative ion easiest
6. Because chlorine (atom) is smallest OR Outer(most) shell of chlorine least shielded OR Nuclear attraction on electrons of chlorine is greatest
Suggest why the student carried out the reactions in a well ventilated area. (1)
Bromine is toxic
