Unraveling the Mystery: Comparing Neutralisation of HCl and CH3COOH

[Kyoma]

Homework Statement

25 cm³ of 1 mol/dm³ ethanoic acid requires a smaller amount of sodium hydroxide for complete neutralisation than 25 cm³ of 1 mol/dm³ hydrochloric acid.
True or False?

2. The attempt at a solution

I selected true, but I was wrong. Both of them require the same amount of sodium hydroxide. How can this be?

Question 2:

In a dilute sugar solution, sugar molecules are widely separated, moving at random while water molecules are close together, moving at random.
True or False?

Attempt

I selected False. But I was wrong AGAIN! What's the reason?

Could you all help me with my questions. Thanks!

 

[Borek]

I selected true, but I was wrong. Both of them require the same amount of sodium hydroxide. How can this be?

Why do you think they need different amount of base?

Similarly, try to explain your reasoning behind the answer to the second question.

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[Kyoma]

I think they need different bases cause ethanoic acid is a weak acid while HCL is a strong acid, thus you need more NaOH to neutralise a strong acid than a weak acid.

I figured out the second qns though, but I remember a qns vaguely about alcohol being dissolved into water and the mixture seems to have mass that didn't add up to the mass of water and alcohol or something like that. I didn't know whether it is the mass, density or volume that didn't add up.

 

[Borek]

I think they need different bases cause ethanoic acid is a weak acid while HCL is a strong acid, thus you need more NaOH to neutralise a strong acid than a weak acid.

Write reaction equations both for HCl and acetic acid neutralization with NaOH.

How much base needed to neutralize 1 mole of each acid?

I figured out the second qns though, but I remember a qns vaguely about alcohol being dissolved into water and the mixture seems to have mass that didn't add up to the mass of water and alcohol or something like that. I didn't know whether it is the mass, density or volume that didn't add up.

Volume is not additive. Mass is additive, that's mass conservation in action. But I fail to see how volume being not additive is relevant to the question.

 

[Kyoma]

Both require 1 mole... But even if both acids have 1 mole of particles, HCL would have more hydrogen ions since ethanoic acid dissociates partially and there would be CH₃COOH molecules left intact in the water.

I figured out qns 2. Thanks.

 

[Borek]

Both require 1 mole... But even if both acids have 1 mole of particles, HCL would have more hydrogen ions since ethanoic acid dissociates partially and there would be CH₃COOH molecules left intact in the water.

You are mistaking dissociation with neutralization. Yes, pH of HCl solution is lower than pH of acetic acid solution, no, it doesn't mean it requires more base for neutralization.

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