Chem Required Practicals Flashcards
Method for making a volumetric solution
-Calculate mass of required substance to make 250cm^3 of 0.1M solution
-Weigh clean, dry weighing boat on balance
-Zero balance and add approx. mass of substance to boat using spatula
-Zero balance and measure mass of boat and substance
-Transfer contents into clean glass beaker and re-weigh, calculate mass of substance
-Add approx. 100cm^3 distilled water to beaker and stir with glass rod to dissolve all substance
-Use a funnel to transfer solution to volumetric flask, rinse rod, beaker, funnel with distilled water
-Make up to 250cm^3, stopper and invert several times
Method for acid-base titration
-Pour approx. 100cm^3 of standard solution into beaker
-Fill burette with standard solution of known conc.
-Pour approx. 100cm^3 of unknown conc. solution into another beaker
-Use pipette filler and pipette to transfer 25cm^3 to 250cm^3 conical flask
-Add few drops of indicator (phenolphthalein) to conical flask and note initial colour
-Record initial burette reading
-Titrate conical flask, add burette solution until permanent colour change, record final burette reading and calculate volume transferred
-Repeat until two concordant titres, calculate mean
Method for measuring enthalpy change
-Weigh out roughly 4g anhydrous copper (II) sulfate in a dry, stoppered weighing bottle
-Make table to record temperatures at minute intervals for 15 minutes
-Use measuring cylinder to put 25cm^3 distilled water into polystyrene cup and record initial temp.
-Start timer and record temp. each minute for 3 minutes
-At fourth minute, add anhydrous copper (II) sulfate to water without measuring temp.
-From fifth minute onwards, record temp. every minute until 15 mins, stirring solution
-Plot temp. against time and draw two lines of best fit, extrapolating both to t=4 and calculate change in temp. at t=4
Method for investigating effect of temperature on rate of reaction
-Add about 10cm^3 1M HCl to acid tube
