Question

2. Potassium bromide and sulfur dibromide both dissolve in water. Draw a diagram showing how potassium bromide dissolves in water, including at least 4 water molecules (30) b) Describe the main difference between dissolving of potassium bromide in water, and dissolving of sulfur dibromide in water. (20) (21) 3. a) Determine the total and net ionic equations for the reaction below L,CO3(a) + 2 HBr → CO, +1,0, + 2 LiBr) b) Identify the spectator ion(s) in the reaction. (1T) c) Describe the total ionic equation for a situation where two ionic compounds do not react with cach other. (1K)

Answer 1

2.

a)

Potassium bromide ( KBr) is an ionic compound. In aqueous solution it dissociates into its ions K+ and Br- , which are attracted by the polar water molecules. The positively charged K+ ion will be surrounded by the negative end of the water molecule ( the O of H2O) and the negatively charged Br- will be surrounded by the H of H2O.

H₂ polar water molecule 4:0: St St H н kt Be K Br = TIT = + K Br КВх in water Bre ion. (Dissolved KB) Surrounded H of H₂O by magnified kt ion. surrounded by negative part of H₂O (Undissolved KB) undissolved KBн (қВх юluch 4 in the process ocess of in dissolving)

The H2O molecules come in-between the K+ and Br- ions and drive them apart, thus dissolving KBr. Here, hydrated ions are formed when dissolving.

(b) Sulfur dibromide (SBr2) is a covalent compound. When it is added to water, it won't form ions , unlike KBr. Here,the water molecules surround each SBr2 molecule as a whole, by orienting the positive pole (H+) near the negative part (the two Br) of SBr2 and the negative part of H2O is oriented around S of SBr2. Thus, unlike KBr, the water molecules surround the entire molecule, and drive them further away to dissolve it. No hydrated ions are formed. The solubility of SBr2 will depend upon how strong the intermolecular forces of attraction between SBr2 and H2O are, and how weak the SBr2 - SBr2 intermolecular forces are.