Paper 1 Pag Flashcards
Measurement of mass: how to establish formula of salt and show water of crystallisation
- record mass of crucible, add X to crucible and record mass
- heat crucible for 2 minutes, allow to cool and reweigh, heat until constant mass so all waters of crystallisation are removed
- calculate everything
Measurement of volume of gas
- use of gas syringe
- inverted measuring cylinder
Making a standard solution
- calculate specific mass needed, add to a beaker and add distilled water and mix until dissolved
- transfer to 250cm3 volumetric flask, add distilled water to graduation line, invert to mix properly
- make sure you add all washings along the way from apparatus used
How to carry out a titration
- rinse burette with a small quantity of distilled water followed by acid, ensuring tap is closed
- pipette 25cm3 of base into a clean conical flask
- carry out titration adding 1cm3 of acid each time until colour changes (due to indicator)
- continue until 2 concordant results
Plan how to establish a value of enthalpy change of neutralisation
- measure out 50cm3 of acid and 50cm3 of base
- allow solutions to reach same temperature by leaving to stand for 5 minutes
- measure temperature
- add them to polystyrene cup one by one and measure max temperature reached
Other enthalpy determination scenarios
- combustion, mass of water heated by fuel, temperature rise and moles of fuel burnt
- reaction, need to know mass of solution, temperature rise and moles of limiting reagent
How to identify 5 different solutions
- add nitric acid, effervescence if carbonate is present
- add barium chloride, if white ppt forms then sulfate is present
- add AgNO3, white: chloride, cream: bromine, yellow: iodine. Can verify with dilute/conc ammonia
- add NaOH, litmus paper turns damp blue if ammonia has produced
Why is CaSH carried out in the order it is?
- neither sulfate or slide ions produce gas with acid so carbonate first
- carbonate ions also give white ppt with barium
- both carbonate and sulfate ions give ppt with silver ions
Outline an experimental setup that could be used to measure the standard cell potential of an electrochemical cell, include labelled diagram, apparatus, solutions and standard conditions
- should know diagram, beakers electrode solution salt bridge wire voltmeter
- solutions and what electrode made of
- 298K and 1moldm-3
Outline a method using continuous monitoring to show reaction is first order (gas collection)
- measure out an excess of an acid using measuring cylinder and transfer to conical flask
- measure mass of X
- add X to acid and fit delivery tube+gas syringe
- record volume at regular intervals
- repeat experiment using different conc of acid
- plot graphs of volume of H2 produced against time, calculate initial rate of reaction by drawing tangets
- compare gradients, if first order then as conc is halved, so will the rate
Plan experiment to find order of this reaction with respect to I-. Use of KI, K2S2O8, Na2S2O3, starch indicator, distilled water
- using a burette, measure out 5cm3 of KI, 2cm3 of Na2S2O3 and 1cm3 of starch into a test tube
- in a separate test tube measure out 2cm3 of K2S2O8
- add the 2cm3 of K2S2O8 and start timing, record time when blue black colour appears showing iodine is present
- repeat procedure using different volumes of KI and H2O, 4:1 3:2 2:3 1:4
- calculate concentration and plot a graph of initial rate against [I-]. Initial rate=1/time
- straight line graph shows first order
