Which of the following is the weakest acid?

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BlackTom AI · Accepted Answer

Question restatement: Which of the following is the weakest acid? Options: HN3 (pKa = 4.72), HF (pKa = 3.14), HOBr (pKa = 8.60), HNO2 (pKa = 3.35), HOCN (pKa = 3.46).

Option 1: HN3 (pKa = 4.72). A higher pKa indicates a weaker acid. However, 4.72 is lower than several other pKa values in this list, meaning HN3 is stronger than those with larger pKa values. Since our target is the weakest (largest pKa), this option is not the weakest among the set.

Option 2: HF (pKa = 3.14). This is a very strong acid in the context of hydrohalic acids, with a low pKa. Compared to the other values here, HF is significantly stronger, so it is not the weakest acid in this list.

Option 3: HOBr (pKa = 8.60). A pKa of 8.60 is substantially higher than the others listed, indicating a much weaker acid. In acid–base terms, the conjugate base is relatively stable and the equilibrium lies far toward the undissociated acid, making HOBr the weakest among these options.

Option 4: HNO2 (pKa = 3.35). With a pKa well below 5, nitrous acid is clearly stronger than HOBr and other higher-pKa candidates, so this is not the weakest acid here.

Option 5: HOCN (pKa = 3.46). This value is also in the strong-acid side relative to HOBr’s 8.60, so HOCN is not the weakest.

Summary perspective: When comparing acidity, higher pKa corresponds to weaker acidity. Among the listed pKa values, 8.60 for HOBr is the largest, while the others fall between about 3.14 and 4.72. Therefore, HOBr has the weakest acidity in this set.

Which of the following is the weakest acid?

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Question at position 29 What distinguishes a weak acid from a strong acid?Weak acids completely dissociate into ions in solutionWeak acids have higher acidity than strong acidsWeak acids release more hydrogen ions in water than strong acidsWeak acids only partially ionize in water

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Which of the following is the weakest acid?

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Which of the following weak acids would produce more hydronium ion when placed in water?

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