2. Suppose that a student doing this experiment failed to dry the KHP before usi

Question

2. Suppose that a student doing this experiment failed to dry the KHP before using it to standardize the 3.98x /0-1 NaOH solution. (a) would her calculated molarity of the NaOH solution probably be too high or too low? Briefly explain. acid? Briefly explain. explain. (b) How would the error you described in (a) affect the calculated equivalent mass of the unknown (c) How would the error you described in (a) affect the calculated Ka of the unknown acid? Briefly mol too high. Inurcs Ture is o intluens berouse the mks of KHP Ouevilt woesne caculodion of 125

Explanation / Answer

2. If student failed to dry KHP before making primary standard solution,

(a) He would have weighed actual less amount of KHP to make standard solution. So the amount of NaOH solution needed to neutralize this KHP would also be less. Therefore, the calculated molarity of NaOH solution would be too low.

If grams of KHP (actual) in total weighted not dry KHP was less

moles = g/molar mass would also be low

moles of NaOH = moles of KHP would be low

It will use less volume of NaOH to reach end point in titration

So, low molarity of NaOH calculated.

(b) The above error would give an error in equivalent mass of acid. The calculated value would be too high. This is because we would have ued less amount of NaOH to neutralize the acid and to get molecular mass of acid.

(c) Ka for the acid would remain unaffected it this case as this.

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