Nitrosyl bromide decomposes according to the following equation - HSC - SSCE Chemistry - Question 13 - 2022 - Paper 1

At equilibrium, the concentration of NOBR decreases to 0.46 mol, which means:

$\Delta[NOBR] = 0.64 - 0.46 = 0.18 \text{ mol L}^{-1}$

Since the decomposition reaction produces 2 moles of NO and 1 mole of Br2 for every 2 moles of NOBR that decomposes, we can set up the following ratio.

From the balanced equation, for every 2 moles of NOBR decomposed, 2 moles of NO are produced:

$[NO] = 2 \times (0.18 \text{ mol L}^{-1}) = 0.36 \text{ mol L}^{-1}$

From the balanced equation, for every 2 moles of NOBR decomposed, 1 mole of Br2 is produced:

$[Br_2] = 0.18 \text{ mol L}^{-1}$

Thus, the final concentrations at equilibrium are:

• $[NO] = 0.36 \text{ mol L}^{-1}$
• $[Br_2] = 0.18 \text{ mol L}^{-1}$