Experimental Design Objectives • Name appropriate apparatus for the measurement of time, temperature, mass and volume including burettes, pipettes, measuring cylinders and gas syringes. • Suggest suitable apparatus, given relevant information, for a variety of simple experiments, including collection of gases and measurement of rates of reaction. Measuring Time Name of SI Symbol of Other Units Instrument Used unit SI Unit for Measurement Seconds s Minutes (min) •Digital stopwatch Hour (h) •Analogue stopwatch •stopclock analogue stopclock digital stopwatch stopwatch Measuring Temperature Name of SI Symbol of Other Units Instrument Used unit SI Unit for Measurement Kelvin K degree Celsius (oC) •Lab thermometer •Data logger with temperature sensor • 0 oC= 273 K • Temp in K = Temp in oC+ 273 laboratory thermometer data logger with temperature sensor Measuring Mass Name of SI Symbol of Other Units Instrument Used unit SI Unit for Measurement Kilogram Kg Grams (g) •Beam balance •Electronic balance beam balance electronic balance Measuring Volume • Experiments may involve liquids or gases. • Apparatus often depends on accuracy required. Measuring Volume of Liquids Name of SI Symbol Instruments Accuracy unit of SI Used for Unit Msrmnt Cubic meter m3 Beaker •To estimate the volume of a liquid e.g. approximately 100 cm3 Measuring cylinder •More accurate than beakser •Measures out volume to nearest ±cm3, e.g. 99 cm3 Burette •Accurately measures out the volume to nearest ±0.1 cm3 Pipette •Accurately measures out fixed volumes of liquids e.g. 20.0 cm3 or 25.0 cm3 Measuring Volume of Liquids pipettes burette beaker measuring cylinder Wake Up Call 1 1 Which of the apparatus listed below should be used to measure 23.0 cm3 of a liquid? A burette and a measuring cylinder B burette only C pipette D beaker Answer: B Wake Up Call 1 2 Name one suitable of laboratory apparatus for (a) Measuring the volume of about 80 cm3 of liquid (b) Adding exactly 18.50 cm3 of liquid into a beaker (c) Collecting and measuring 80 cm3 of a gas (d) Adding exactly 25.0 cm3 of a solution into a flask Collecting Gases and Measuring Volume of Gases • Method for collecting gases depends on – Solubility in water – Density (compared to air) Gas Solubility in water Density compared to air ammonia extremely soluble less dense hydrogen chloride very soluble denser sulfur dioxide very soluble denser chlorine soluble denser oxygen slightly soluble slightly denser carbon dioxide slightly soluble denser hydrogen insoluble less dense Collecting gases • Methods of collecting gases Measuring the Volume of a Gas Name of SI Symbol of Other Units Instrument Used unit SI Unit for Measurement Cubic meter m3 dm3, cm3 •Gas syringe •Measures a maximum of 100 cm3 of gas barrel plunger Wake Up Call 2 1) A mixture of gases include hydrogen and water vapour. Arrange a series of apparatus to collect a pure, dry sample of hydrogen. Ans: 1,2,7 2) Gas X is denser than air and insoluble in water. It can be dried using the same drying agent for ammonia. Gas Y is water soluble. Arrange a series of apparatus to collect a pure, dry sample of gas X from a mixture of both gases. Ans: 1,3,5 Wake Up Call 2 • 3) Hydrogen chloride is very soluble in water, whereas chlorine is only slightly soluble in water. Both gases can be dried using the same drying agent. Arrange a series of apparatus to collect dry chlorine from damp chlorine containing a small amount of hydrogen chloride. Ans: 1,3,5 Summary Quantity Apparatus SI unit Other units Time stopwatch second (s) minutes (min) stopclock hours (h) Temperature thermometer Kelvin (K) degree Celsius data logger with (oC) temperature sensor Mass beam balance Kilogram (kg) gram (g) electronic balance Volume of beaker, measuring cubic metre litre (L), millilitre liquid cylinder, burette, (m3) (ml), cubic pipette centimeter (cm3) Volume of gas syringe cubic decimeter (dm3).