You're viewing 1 free preview question for Chemistry SL — subscribe to unlock 86 more, plus the Full Question Bank, Mock Papers & Worksheets.Upgrade

Electron-Pair Sharing Reactions · Paper 2 — Free Chemistry SL Practice Questions

1MasterySAQ-SCoordinate covalent bonding5 marksPaper 2~8 min
Ammonia (NH3\text{NH}_3) can act as a Lewis base and form a coordinate bond with boron trifluoride (BF3\text{BF}_3), producing the adduct H3N ⁣⋅ ⁣BF3\text{H}_3\text{N} \!\cdot\! \text{BF}_3.
(a)
State which atom in NH3\text{NH}_3 acts as the electron pair donor and which atom in BF3\text{BF}_3 acts as the electron pair acceptor. [1 mark]
(b)
The bond enthalpy of the N–B coordinate bond in H3N ⁣⋅ ⁣BF3\text{H}_3\text{N} \!\cdot\! \text{BF}_3 is 155 kJ mol−1155\,\text{kJ mol}^{-1}. A sample of 0.0500 mol0.0500\,\text{mol} of H3N ⁣⋅ ⁣BF3\text{H}_3\text{N} \!\cdot\! \text{BF}_3 is formed from its gaseous components. Calculate the total energy change, in kJ, for this process, considering only the formation of the coordinate bond. State whether energy is released or absorbed. [2 marks]
(c)
Explain why the geometry around the boron atom changes from trigonal planar in BF3\text{BF}_3 to tetrahedral in H3N ⁣⋅ ⁣BF3\text{H}_3\text{N} \!\cdot\! \text{BF}_3. [2 marks]
diagram

Solutions

Questions 2-87

Unlock these questions with Premium

Sign Up →

That's every free question here — 1 of 87.

+86 more questions, plus Mock Papers & Worksheets, are waiting in Premium.

Upgrade