2009 Midterm

A k and clo b h and oh c none d k e h k clo

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Unformatted text preview: reaction? A) K+ and ClO-; B) H+ and OH-; C) none; D) K+; E) H+, K+, ClO- and OH-. To answer the question, we need to write the total ionic equation and indicate which ions are found both on the left and on the right sides of it. Furthermore, since this is an acid-base reaction, we need to consider if we have a strong or weak acid and a strong or weak base. Here we have a strong base KOH (aq) but a weak acid HClO (aq). A weak acid does not fully dissociate into ions. Therefore, the net ionic equation is: HClO (aq) + K+ (aq) + OH- (aq) → K+ (aq) + ClO- (aq) + H2O (l). The spectator ions are K+. Chemistry 1024b, Winter 2009 Midterm Exam with Solutions Page 6 out of 9 18. Consider the following 4 reactions. Which of those are NOT acid-base reactions? (1) H2SO4 (aq) + KOH (aq) → K2SO4 (aq) + H2O (l); (2) CO2 (g) + KOH (aq) → K2CO3 (aq) + H2O (l); (3) MnO2 (s) + O2 (g)+ KOH (aq) → K2MnO4 (aq) + H2O (l); (4) MgO (s) + H2SO4 (aq) → MgSO4 (aq) + H2O (l). A) 1; B) 2; C) 3; D) 2 and 3; E) 3 and 4. Acid-base reactions can occur not only between classic acids and bases but also between acidic and basic oxides, or an acidic oxide and a base, or a basic oxide and an acid. Basic oxides are oxides that produce OH- ions in aqueous solutions, like classic bases do, and thus they are bases according to the Arrhenius definition (MS5, p. 82). Examples are CaO, MgO, K2O, etc. K2O (s) + H2O (l) → 2 KOH (aq) Correspondingly, acidic oxides are oxides that produce H+ ions in aqueous solutions, similar to classic acids: SO2 (g) + H2O (l) → H2SO3 (aq) Reaction 1 is a classic acid-base reaction of a strong acid and a strong base. Reaction 2 is a reaction between a strong base KOH (aq) and an acidic oxide and thus is also an acid-base reaction. Reaction 4 is a reaction between a strong acid H2SO4 (aq) and a basic oxide and thus is an acid-base reaction too. The only reaction that is not an acid-base reaction but rather a redox reaction is reaction 3. 19. Consider the following 4 reactions. Which of those are oxid...
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This note was uploaded on 02/13/2014 for the course CHEM 1024 taught by Professor Dr.zhifengding during the Winter '12 term at UWO.

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