TITRATION CALCULATIONS! C3 please help

I learn the equation:
Moles = concentration X volume

ALWAYS remember If you're given a volume in cm*3 then divide it by 1000 to get it into dm*3

Firstly find out whatever you can from the information they provide, they usually give the concentration and volume so you can work out the moles

The moles is the same for both the reactants so substitute the moles into the equation to find the missing concentration/volume

Concentration is: moles divided by volume
Volume: moles divided my concentration

It's so hard to explain by typing 😂

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Reply 2

scphmapd

Original post by z1820

Great description! That is so helpful.

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Reply 3

Imsophie

Original post by jazz_xox_

please can someone list a method of finding titration calculations?
the CGP book and my-gcsescience.com do it different ways and i'm so confused :frown:

thank you!

Usually you'll be given the volume and concentration of one of the reactants and the volume or concentration of the other.
Think of it as a neutralisation equation
25cm3 of 0.1 moldm3 HCI reacts with 22.5cm3 of NaOH
NaOH + HCI ----- NaCI + H2O
1) ensure equation is balanced.
2) I usually next write out a table, the two headings are the reactants: moles, volume and concentration need to be worked out.
Considering your always given the concentration and volume one reactant you can work out the number of moles. In the example: moles = conc X volume (0.1 X (25/1000) = 0.0025 moles
3) work out moles of other reactant. This is done by looking at the big numbers in front of the reactants 1HCI reacts with 1NaOH. Therefore there is a 1:1 ratio and the number of moles of HCI = moles of NaOH
Now you have NaOH moles (and given volume of 22cm3) you can work out concentration
0.0025/0.0022=1.13 moldm3 I think the working out is right but the method definitely is
Just remember your always given the volume and concentration of one. Multiply them to get moles. Use balanced equation to work out the number of moles of other reactant which you can then divide to work out either the concentration or volume
Hope this helped

Reply 4

Original post by z1820

thank you very much! this is how the my-gcsescience guy does it, but the text book confused me!
could you write down for the acid and alkali
concentration x volume = concentration x volume
because the moles are the same for each side? (this is if they want you to find a missing concentration or volume?)

thanks again

Reply 5

Original post by scphmapd

Great description! That is so helpful.

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Just forgot to mention that the moles is that same if they both have the same number behind their formula

E.g.

2Na + 1Li

They don't have the same number of moles, Na has twice has many - say if you work out the moles of Sodium (Na) is 0.4 all you have to do is divide by 2 to get lithium (because it's half)

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Reply 6

Original post by jazz_xox_

SORRY! (edit)

forgot to mention that the moles is the same if they both have the same number behind their formula

E.g.

2Na + 1Li

They don't have the same number of moles, Na has twice has many - say if you work out the moles of Sodium (Na) is 0.4 all you have to do is divide by 2 to get lithium (because it's half)

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Reply 7

Original post by z1820

thank you ! would we be able to do a question together so i can be confident im doing it right?

Reply 8

Original post by jazz_xox_

thank you ! would we be able to do a question together so i can be confident im doing it right?

Of course

Reply 9

Original post by z1820

Of course

27.5 cm3 of 0.2 mol/dm3 hydrochloric acid is needed to titrate 25.0 cm3 of sodium hydroxide solution. What is the concentration of the sodium hydroxide solution?

Reply 10

Original post by jazz_xox_

27.5 cm3 of 0.2 mol/dm3 hydrochloric acid is needed to titrate 25.0 cm3 of sodium hydroxide solution. What is the concentration of the sodium hydroxide solution?

I got 0.22 mol/dm^3

Reply 11

Original post by jazz_xox_

I got 0.22 mol/dm^3

ImageUploadedByStudent Room1465941352.333539.jpg

Me too! (I hope it's right hahah)

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Reply 12

Original post by z1820

Me too! (I hope it's right hahah)

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Sorry my units are wrong should be mol/dm*3

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Reply 13

Original post by z1820

Sorry my units are wrong should be mol/dm*3

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Yay! thank you so much for your help, actually want one of these to come up now! good luck in your exam :smile:

Reply 14

Original post by jazz_xox_

Yay! thank you so much for your help, actually want one of these to come up now! good luck in your exam :smile:

No problem, well done for learning so fast - they're really tricky! I think at least one question will come up on titration calculations & thank you, good luck to you too :smile:

Reply 15

Original post by z1820

No problem, well done for learning so fast - they're really tricky! I think at least one question will come up on titration calculations & thank you, good luck to you too :smile:

I think where I was going wrong is I wasn't dividing by 1000 first :biggrin:

Reply 16

Original post by jazz_xox_

I think where I was going wrong is I wasn't dividing by 1000 first :biggrin:

Oh I see ahaha
Are you feeling prepared for the exams?

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Reply 17

Original post by z1820

Oh I see ahaha
Are you feeling prepared for the exams?

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Kind of, I'm nervous for C2 tbh because we have only had one (yes, one) lesson on C3 so I've been teaching myself that- but I got an A* in my C2 mock so fingers crossed! are you?

also someone just posted this question could you help? its fine if you dont want to its getting late
The equation for the reaction is

CaCO3(s) → CaO(s) + CO2(g)
Calculate the maximum mass of calcium oxide that can be obtained by
heating 25 tonnes of calcium carbonate.
(Relative atomic masses: C = 12, O = 16, Ca = 40)

[The answer is 25 (tonnes) gives 56x25 (tonnes)]

Reply 18

Original post by jazz_xox_

Hmmm there's 2 ways but:

25 tonnes -------> ?
Mr: (adding all the relative atomic masses)
CaCo3----->CaO
100 ------> 56

100 X 0.56 = 56
So 25 X 0.56 = 14

0.56 X 25 = 14 tonnes ?

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(edited 7 years ago)

Reply 19