Required Practicals - Inorganic and Physical
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Describe how you would create a 250cm3 standard aqueous solution of a substance RP1
• Accuratley weigh out a dry sample of substance using a high precission balance into a clean, dry weighing boat • Transfer to a beaker and reweigh weighing boat to determine mass transfered • Dissolve substance in small volume of distilled water • Transfer to a 250cm3 volumetric flask and rinse the beaker, transferring the washings as well. • Add distilled water up to callibration line, using a dropping pipette at the end. Ensure the miniscus rests on the callibration line. • Add a stopper and invert 10 times.
Describe a method for determing the concentration of an unknown solution of HCl, using a 0.1 moldm-3 solution of NaOH in an acid base titration RP1
• Set up apparatus and rinse the burette with NaOH into a waste beaker. Ensure the jet space is filled with NaOH. • Measure out a known volume of HCl into a conical flask, e.g. 25cm3, using a volumetric pipette • Add a few drops of a suitable indicator • Slowly add the NaOH to the acid, swirly between additons until the indicator changes colour • Record the volume of NaOH added and repeat until concordant results are achieved. • Using the mean titre to calcultae concentration of HCl
Describe how to measure the enthalpy change when a solid disoolves in water. RP2
• measure out a precise volume of water into a polystyrene cup with a lid using a volumetric pipette, e.g. 50cm3 • Weigh out a precise volume of solid using a high precision balance, e.g. 4.00g, in a weighing boat • Measure the initial temperature of the water using a precise thermometer every minute for 4 consecutive minutes • Pour solid into weighing boat at minute 5 and replace lid, no temperature is recorded • Reweigh weighing boat to calculate mass transferred • Continue to record the temperature at minute intervals for 15 minutes • Plot a graph and extrapolate the two lines of best fit to find the temperature change at 5 minutes • use q=mc^T and ^H=q/moles to calculate enthalpy change
Describe how you would measure the enthalpy change of combustion of a substance RP2
• Place the substance in a liquid burner and weigh the initial mass, using a precise balance. • Accuratley measure a large volume of water (100cm3) into a calorimeter, and record the initial temperature using a precise thermometer. • Light the wick of the burner, and burn until a significant temperature change has occured. Record this temperature change. • Reweigh the spirit burner and calculate mass burnt • Use q=mc^T and ^H= q/moles to calculate enthalpy change
Draw a electrochemical cell experiment RP8
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Draw a pH titration curve for a strong acid with a strong base RP9
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Draw a pH titration curve for a strong acid with a weak base RP9
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Draw a pH titration curve for a weak acid and a strong base RP9
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Draw a pH titration curve for a weak acid with a weak base RP9
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Describe how to draw a pH titration curve RP9
• Draw a callibration curve by finding the pH of known pH solutions using a pH probe. Draw a graph so actual values can be estimated during the titration • Measure the initial pH, and then rercord the pH after every 1cm3 of solution has been added until the equivilance point is neared. • Then measure the pH after adding 0.1cm3 at a time. • Plot a graph of pH against volume added, this is the pH titration curve.