B. Le Châtelier\'s Principle in acid and base solutions 1. Pour 5 mL of 1 M acet
ID: 696512 • Letter: B
Question
B. Le Châtelier's Principle in acid and base solutions 1. Pour 5 mL of 1 M acetic acid into each of two test tubes, labeled #1 and #2. Add 2 drops of methyl orange to each test tube. Record the color of the solutions. 2. Add 1 scoop of solid sodium acetate, NaC2H302 to test tube #1. Shake. Record the color: The equilibrium involved is HC2H3O2 Yellow orange ionizes readily in solution. Explain the color change in terms of Le Châtelier's Principles: So dium acetate is a soluble salt that i Did the solution become more acidic or basic when sodium acetate was added?Explanation / Answer
The equilibrium is
CH3COOH <-------> H+ + CH3COO-
(Yellow) (orange)
When sodium acetate (CH3COONa) is added, that is the product is added.
LeChatelier's principle states that if a dynamic equilibrium is disturbed by changing the conditions, the position of equilibrium shifts to counteract the change to re-establish an equilibrium. If a chemical reaction is at equilibrium and experiences a change in pressure, temperature, or concentration of products or reactants, the equilibrium shifts in the opposite direction to counteract the change.
In this case, the equilibrium position will move so that the concentration of CH3COONa (that is CH3COO-) decreases again by reacting it with H+ to form more CH3COOH. Hence, the equilibrium moves to the left side.
The color of CH3COOH is yellow, so the solution color will become more yellow.
Lower the pH, higher the acidic.
Again pH = - log[H+].
More the [H+] concentration, less will be the pH and hence more the acidic.
When we add CH3COONa (that is CH3COO-), it reacts with [H+] to form CH3COOH. So, the concentration of [H+] is decreasing. Hence pH will be higher.
So, the solution will be less acidic after adding CH3COONa to the original solution.
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