Calculating Amount of H2SO4 Needed to Neutralize NaOH

[chawki]

Homework Statement

To completely neutralise 1 mol, i.e. 40.0 g, of sodium hydroxide (NaOH),
1 mol, i.e. 36.5 g, of hydrochloric acid (HCl) is required. Determine the amount (using the units
mol and gram) of sulphuric acid (H₂SO₄) required to neutralise the same amount of sodium
hydroxide.

Homework Equations

Write the equation for this reaction.

The Attempt at a Solution

I really have no idea what they are talking about.

 

[Borek]

As told - start with the reaction equations. How does HCl react with NaOH? How does H₂SO₄ react with NaOH?

 

[chawki]

Hello Borek.

After some research, i found that the reaction should be like this:
2 NaOH + H₂SO₄ -------> Na₂SO₄ + 2 H₂O.

However is this the final answer ? i don't get why they gave information on HCl and NaOH

 

[Borek]

However is this the final answer ?

How can it be the final answer, have you read the question? You are asked to determine the amount, reaction equation is not the amount of the substance.

I asked you to write TWO reaction equations.

 

[chawki]

The first reaction is
NaOH + HCl ---------> NaCl + H₂O

 

[Borek]

OK. In fact this reaction is not necessary to solve the problem, but it nicely shows how acid base reactions are related - they produce salt and water. Compare both reactions to see what I am talking about.

Now concentrate on the first reaction - the one between NaOH and H₂SO₄. Do you know how to read the reaction equation? Can you tell how many moles of sulfuric acid reacts with ONE mole of NaOH?

 

[chawki]

one mole.

 

[Borek]

No. Look at stoichiometric coefficients.

 

[chawki]

0.5mole

 

[chawki]

still convinced it's 0.5 mol

 

[Borek]

Good for you.

 

[chawki]

so that's the answer ?
0,5 mol of sulphuric acid ?

 

[Borek]

Yes, sulfuric acid has two acidic protons, so it reacts 1:2 with NaOH.

 

[chawki]

that's very surprising..i wasn't expecting this small answer..and i was expecting more complicated things since they gave us many data

the whole answer to this excercise is just the equation:
2 NaOH + H₂SO₄ ----> Na₂SO₄ + 2 H₂O

and the amount of H₂SO₄ is 0.5 mol ?
by the way, what do they mean by ''same amount of NaOH''

 

[Borek]

Same amount of NaOH - identical amount of NaOH, just like 40g that reacted with HCl.