A procedure is conducted to observe the buffering capacity of a sodium acetate/a

Question

A procedure is conducted to observe the buffering capacity of a sodium acetate/acetic acid solution at pH=4.5. Consider the errors that may occur during this procedure and determine whether each error would affect the pH (or apparent pH) of the buffer solution, the buffering capacity of the solution, both values, or neither value.

A procedure is conducted to observe the buffering capacity of a sodium acetate/acetic acid solution at pH-4.5. Consider the errors that may occur during this procedure and determine whether each error would affect the pH (or apparent pH) of the buffer solution, the buffering capacity of the solution, both values, or neither value Buffering capacity pH/apparent pH and buffering capacity pH/Apparent pH Neither The pH meter The overall solution molarity A 0.01 M buffer solution is correct, but the ratio ofis prepared instead of before being used. sodium acetate to acetic acid a 0.1 M buffer solution. is not calibrated concentrations is off by 5%. Acetic acid is unavailable, so formic acid and sodium acetate are used to prepare the buffer. The pH probe is not rinsed after calibration with the pH=7 standard solution

Explanation / Answer

Sr. No. Errors pH/Apparent pH Buffering capacity pH/Apparent pH and buffering capacity Neither 1 The pH meter is not calibrated before being used. Yes, because the solution used in the previous experiment react with the sodium acetate and the pH value appear will be different from the original one. Yes, due to change in the pH of buffer, the capacity of buffer will reduce due to change in the pH. Both values will be affected. - 2 The overall solution molarity is correct, but the ratio of sodium acetate to acetic acid concentrations is off by 5%. No, for pH=4.5, the ratio of sodium acetate and acetic acid should be 1.76, if the ratio changes by 5% then the pH of the buffer will remain within 1 unit of pKa, i.e. the pH won't change by very much and the solution is therefore buffered. No, as the pH of the buffer won't change very much, thus its buffer capacity will also not change much. - Neither of the value changes. 3 A 0.01M buffer solution is prepared instead of a 0.1M buffer solution. Yes, pH will change, pH of the buffer depends on the concentration of weak acid and conjugate base. Yes, buffering capacity will change,Buffer capacity depends on the amounts of the weak acid and its conjugate base that are in a buffer mixture. If the concentration changes the buffer capacity will also change. Both value will change. - 4 Acetic acid is unavailable, so formic acid and sodium actate are used to prepare the buffer. Yes, formic acid is stronger acid than ethanoic acid. Yes, as th pH of the buffer changes the buffering capacity will also change. Yes, both value will get change. - 5 The pH probe is not rinsed after calibration with the pH=7 standard solution. Yes, the pH probe should be rinsed properly using distilled water or pH=7 standard solution, so as the pH of buffer will not get affect. Yes, if the pH probe is not rinsed, it will still show th reading of previous solution used. Yes, both will change. -

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