4.2

Question 1

What can titrations be used for?

Answer 1

Finding concentration of a solution
Identification of unknown chemicals
Finding the purity of a substance

Question 2

Volumetric flasks can…

Answer 2

Be used to make up standard solutions very accurately

Question 3

Uncertainty (tolerance?) of 100cm3 and 250cm3 columetric flask

Answer 3

100cm3: +-0.20cm3
250cm3: +-0.30cm3

Question 4

Method prepare standard solution

Answer 4

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.