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I did some titration today and I just wanted to confirm with you guys my results am I right in thinking that through titration 25cm3 of HCl at 0.1m neutralising 27.50cm3 of NaOH means that the concentration of the NaOH is 9.09% or 2.49cm3 of the 27.50cm3?

Do your own homework

I already did the experiment at college we just didn't have time to calculate the data and I was curious.

Calculate the number of moles of HCl used. C=n/V

To neutralise the NaOH, the HCl must be in 1:1.
Therefore the number of moles of NaOH is the same.

Use that with the volume of the NaOH solution to get the concentration of that solution. C=n/V (I get 0.091M)

I assume you've been asked to get the mole%.
Been a while since I've had to do this, I believe:
Then you need to work out the number of moles of water in the solution. Get that from the density of water and the volume. Compare that to the moles of NaOH.

Being a solid in it's pure form, I don't think you can say that the NaOH is a certain volume of the solution. But this is where my memory gets hazy.

Thanks

Sorry, the extent of my knowledge of titration is poking fun at my science teacher wife by stating that "aren't titrations what you put your baby on when you are trying to wean them off of breast milk?"

She now has to stifle giggles and try desperately not say it "my way" in front of her class every year.

NaOH and HCl react 1:1 ( this is obvious from your chemical equation)

If NaOH was 0.1M you would use 25ml to neutralise 25ml of 0.1M HCl. You are a little off but it's going to be about 0.09M as someone said above. I'd do it as a ratio. They react on a 1:1 basis, but 25ml acid needed 27ml base, (25/27)x100 = 93%. 93% of 0.1M is 0.093M.

That's not the way the textbooks seem to teach it, they seem to ask you work out the actual number of moles reacting. I prefer to think about that ratios of the reactants used and compare to ratio at which they react by equation.

The odds are that if this was a classroom practical set up for you, they were supposed to be both 0.1M. Either you weren't accurate enough doing the titration or one solution was slightly off when prepared or the stock has degraded.




Added to which, if concentrations are in moles, stick to moles when answering or you'll get into knots.

25ml of a 0.1M NaOH solution is not the same as 25ml of a 10% solution, or 9.09% as you said, and does not contain 2.5ml NaOH, for a start because NaOH is a solid.

If you were making a 10% NaOH solution that would be 10g NaOH per 100ml or 2.5g in 25ml. A 0.1M solution of NaOH would have 4g per litre or 0.1g per 25ml.

again thanks

So, I wanted to feel stupid, so I read this thread. Aside from the post by AegisGrimm which made me LoL, I've achieved my goal. I now feel royally lacking in the brain department.

Cool post though, science is all science-y!

I can only say one thing to this thread. It's the same thing one of my class mates said 12 years ago.

BUT LETTERS ARENT NUMBERS!

I'm currently in training to be a chemistry teacher.

what you said:

 Howard A Treesong wrote:
I'm currently in training to be a chemistry teacher.

What I heard

 Howard A Treesong wrote:
Let's cook

It's good to get into the practice of calculating the moles to get to the concentration, as it becomes important for when the numbers aren't so easy and the numbers become very small, as they do in research labs and it's vital to be very accurate.

If it was me running the experiment I would have made the hydroxide solution just slightly off 0.1M to catch out the lazy ones. But I'm evil like that with students.

 Soladrin wrote:
I can only say one thing to this thread. It's the same thing one of my class mates said 12 years ago.

BUT LETTERS ARENT NUMBERS!

They are if you are Roman.
Welcome to year MMXIV.

Now is a Mole that that mexican sauce made with chocolate? Or is that Guacamole? One of them has Avogadros in it….

 Nevelon wrote:
Now is a Mole that that mexican sauce made with chocolate? Or is that Guacamole? One of them has Avogadros in it….

Half of me wants to laugh, half of me weeps.

 Nevelon wrote:
Now is a Mole that that mexican sauce made with chocolate? Or is that Guacamole? One of them has Avogadros in it….

That pun is bad and you should feel good.