HELP! Titrations

[Rowyrow]

Hi all so I thought I had this one under controll!
The yr 11's are doing the Sodium Carbonate Hydrocloric acid titration so I though I would just test my solutions first but I think I have made a major Miscalcultion some where or my conc HCl is not 32% as the label states.
Now I initially made up 1litre of 1M HCl by using adding 98mls of the Conc (32% roughtly 10.2M) HCl to 902ml of distilled water so I'm thinking I have 1 litre of 1M HCL, SO I use this to make up 1 litre of 0.2M HCl so I add 200ml of 1M HCL to 800ml of distilled water, so now im thinking I have 1 litre of 0.2MHCl
Okay so I run the titration i.e. make up standard 0.1M solution of Na₂CO₃ by dissolving 2.64g of Na₂CO₃ in 250mls of water (In a volumetric flask ofcourse). And take 20ml alliquots of this and put it in conicle flask, fill burett with 0.2M HCl (or what I think is 0.2M). Do the tirtation using methyorange and get three HCl volumes 39.4, 39.5 and 39.6!!!!! now clearly something has gone wrong somewhere yes? shouldn't they all be around the 20 ml mark if the Na₂CO₃ is 0.1M and the HCl is 0.2M? because the balaced equation indicates you need two moles or HCl per one mole of Na₂CO₃to reach equivalence?
What calculation did I stuff up?
Help me, they are doing it tomorrow

[Rowyrow]

I Figured it out I mistakenly used a 25ml gradulated pippett instead of the 50ml one that I though I got out. So instead of adding 98ml I only added 48mls. Oh well at least I know there is nothing wrong with my Conc HCl or my calculations I just ned to pay more attention when I'm getting out my glassware!

[smiley]

Better to find out now rather than after a class has spent a whole lesson getting it wrong! Feeling silly in front of us on chemtalk, and feeling silly in front of a class are definitely two different things!