Titration tips for tuesday peps:
1) Take the funnel out of the burret after filling
2) Record results to 2 dp always the last number must end in a 5 or 0.
3)As soon as there is a colour change stop and mix the concial flask. If the colour stays the same finsh and record ur result. If it doesnt add drops from the burrete.
Air-bubbles... remove them beforehand! then re-fill burette if you have to.
Read the meniscus at eye-level.
Remove the funnel before titrating.
Your 1st titration should be a rough one: allow 1 cm3 at a time, stop/ start flow method. This is to save time and know roughly around what value the end point titre should be. Remember to swirl the mixture.
For the 2nd titration add the acid in the burette dropwise to the alkali when nearing the rough titration value.
Titrate again. When you have 2 concordant values (within 0.10 cm3 of eachother) stop titrating.
There are 5 attempts max. If you don't find a concordant value by the 5th attempt, make it up!
Questions: when you run acid through the burette to 'clean it' does this mean you have to do the whole 'twirl it 360 degrees' number, or can you just let it run through into a beaker whilst it's clamped in place? Is running through the acid enough, do you have to clean it using distilled water as well?
Indicators: Methyl Orange or phenolphthalein. Do both fulfil the same role?
(Original post by sonsta)
how do you remove air bubbles? what's good way of doing this? and how the hell do you do the planning section on AQA practical exam tips?
To remove air bubbles, run the acid through the burette until the air bubble buggers off, then refill. I've heard of people flicking the burette, but I haven't tried that before so... not sure on that one.
For the glorious Practical... someone on another other thread believes that the plan involves a gas syringe. This means it could involve planning a rates of reaction experiment (varying concentration of reactants, or temperature : Ideal gas equation required here), or a 'prove that the molar ratio in the equation is correct'. Have a look at this http://www.zshare.net/download/gas-syringes-doc.html
Ofcourse whether the rumour is true or not is another thing!
when you record your results does the first one HAVE to be a rough titration? Or can you include it in your average titra value as long as it is concordant to the desired dp value? I mean will you get marked down if you use the first titration on the sheet?