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# Titration Calculation - Any help much appriciated! watch

1. I am about to start A Level Chemistry in september and our teacher has given us some preparatory work involving back-titration to do over the Summer which I have tried but have now become very stuck on... any help as to what I am supposed to do (and the meaning of 1M and 0.1M) would be very helpful!

The Experiment
- Measure 10cm³ of the Milk of Magnesia (active ingrediant is Mg(OH)₂ ) into a 250cm³ volumetric flask
- Pipette 50cm³ of 1M hydrolchloric acid into the volumetric flask and shake the contents
- Top up with distilled water to the 250cm³ mark
- Pipette 25cm³ of this solution into a conical flask and add a few drops of methyl-orange indicator
- Prepare a burette with 0.1M sodium hydroxide solution and add this alkali to the contents of the conical flask and record how much needs to be added until the end-point
- Repeat to obtain concordant results

Results
- after repeating the experiment and taking an average, our result was 25.3 cm³ of sodium hydroxide solution needed to be added to neutralise the solution in the conical flask

Calculate/ Find:
- the no. of moles of HCl added to the M' of M' in 50cm³ of 1M HCl
- the no. of moles in the mean titre of 0.1M NaOH
- a symbol eq. for the neutralisation of NaOH with HCl
- how many moles of excess HCl are present in the 25cm³ aliquot and therefore the 250cm³ sample
- the no. of moles of HCl which reacted with the M' of M' (reacted=total-excess)
- an eq. for the neutralisation of Mg(OH)₂ with HCl
- the no. of moles and mass in grammes of Mg(OH)₂ in the 10ml sample

Any help would be very much appriciated!
Thank you,
Katie x
2. moles of HCL added = 1 x (50/1000)
mean titre = 1.0 x (25.3/1000)
Equation = you should be able to do that, its a 1:1 ratio btw

i can do the rest but cant be bothered sorry, generally remember its a 1:1 ratio so finding out number moles of NaOH used will give you pretty much everything you need.
3. symbol eq- NaOH + HCl -> NaCl + H2O
4. Thank you! So what does the 1M HCl and 0.1M NaOH actually mean? x
5. 1 M = 1 molar = 1 mole per litre = 1 mol dm-3
6. ahhh okkk! that makes so much more sense now - thats where you get the concentrations from then! thank youuuu! x

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