[CHEM] Chapter 1.1 Experimental Design

DARRELL ER (COPYRIGHTED) TOPIC 1.1: EXPERIMENTAL DESIGN DARRELL ER (COPYRIGHTED) ©

CHAPTER ANAL YSIS THE ABOUT TIME EXAM WEIGHTAGE DARRELL ER (COPYRIGHTED) ©

EXPERIMENTAL DESIGN APPARATUS FOR MEASUREMENT GAS COLLECTION KEY CONCEPT DARRELL ER (COPYRIGHTED) ©

MUST KNOW APPARATUS FOR MEASUREMENT DARRELL ER (COPYRIGHTED) © Apparatus Smallest division Uncertainty (1/2 of smallest division) Example of value Burette 0.1cm3 0.05 cm3 27.00 cm3 28.85 cm3 Pipette fixed fixed 25.0 cm3 (fixed value) Measuring cylinder 1 cm3 0.5 cm3 16.0 cm3 17.5 cm3 Digital stopwatch 0.01s 0.01s 26.46 s 1.5 mins Thermometer 1oC 0.5 oC 21.0 oC 46.5 oC Electronic balance 0.01g 0.01g 4.53 g

DISPLACEMENT OF WATER KEY CONCEPT This method for collecting gases which are insoluble or slightly soluble in water. As the gases does not dissolve in water, they would rise to the top of the gas jar. Some examples of gases collected via this method includes H2, O2, CO and CO2. DARRELL ER (COPYRIGHTED) ©

UPWARDS DELIVERY KEY CONCEPT This method is used to collect gases which have a lighter density as compared to air*. NH3 & H2 are gases which can be collected using this method. * Mr of air is around 28.8. (78% N2 + 21% O2) DARRELL ER (COPYRIGHTED) ©

DOWNWARDS DELIVERY KEY CONCEPT This method is used to collect gases which have a heavier density as compared to air*. Some examples of gases collected using this method includes Cl2, HCl and SO2. * Mr of air is around 28.8. (78% N2 + 21% O2) DARRELL ER (COPYRIGHTED) ©

DRYING OF GAS KEY CONCEPT To dry a sample of gas, we can pass it through drying agents like: - concentrated sulfuric acid - quicklime (calcium oxide) - fused calcium chloride (calcium chloride) DARRELL ER (COPYRIGHTED) ©

things to note Concentrated sulfuric acid Quicklime (Calcium Oxide) Fused Calcium Chloride ADVANCED DARRELL ER (COPYRIGHTED) ©

Try it yourself! (TYS Question) Answer: