Question

Experience teaches us that most solids are more soluble in warm water than in cold water. Does the solid utility of Mg(OH)_2 fit this pattern? Briefly explain. Cobalt chloride is used in many weather-forecasting devices. Based on your observations in the laboratory, explain how an alcohol solution of CoCl_2 could be used to predict rain. A student is studying the equilibrium described by the net ionic equation shown in Equation 18. [Cu(H_2O)_6]^2+ (aq, blue) + 4 Br^-(aq) CuBr_4^2+(aq, green) + 6 H_2O(l) (1) The student adds sodium bromide solution (NaBr) to a sample of the blue equilibrium mixture in order to increase the Br^- ion concentration. Predict what the student will observe, and explain your prediction. (2) The student draws some of the blue solution into the bulb of a Beral pipet. The pipet is placed, bulb down, in a hot-water bath. After a short time. the solution changes from blue to green. Is the forward reaction in Equation 18 endothermic or exothermic? Briefly explain. A student is studying the equilibrium described by Equation 19. heat + CoSO_4 middot 7 H_2O(s, pink) + 7 SOCl_2(l) CoSO_4(s, blue) + 7 SO_2(g) + 14 HCl(g) Using microscale techniques and working in a fume hood, the student mixes pink CoSO_4 middot 7 H_2O with SOCl_2 and heats the mixture in a covered container. The solid turns blue. The student removes the cover from the container and stirs the blue solid. After replacing the cover, the student cools the mixture, but observes no color change. Briefly explain the basis for the student's observations.

Answer 1

Question 1.

most solids are soluble as T increases in water.

Note that

Mg(OH)2 will NOT fit this pattern,

actually, the enthalpy of dissolution is exothermic for Mg(OH)2

meaning that more HEAT will favour the solid formation, not the aqueous formation (dissolution)

Which is typical for tap water piping, as T decreases, more preciptate forms