4.2 Flashcards
What can titrations be used for?
Finding concentration of a solution
Identification of unknown chemicals
Finding the purity of a substance
Volumetric flasks can…
Be used to make up standard solutions very accurately
Uncertainty (tolerance?) of 100cm3 and 250cm3 columetric flask
100cm3: +-0.20cm3
250cm3: +-0.30cm3
Method prepare standard solution
Solid first weighed accurately
This then dissolved in less (volume) distilled water than amount needed to fill volumetric flask
Solution transferred to volumetric flask, last traces rinsed off with distilled water
Flask carefully filled up to graduation line drop by drop - too much water (solution dilute), start again
Invert volumetric flask several times, to mix solution thoroughly. If omitted, titration unlikely be consistent. Can see solution mixing when invert flask as more dense original solution moves theough rest of solution.