Experiments 2025 Latest Questions and
simplified correct Answers
Make Up a Volumetric Solution - correct answer-1. Place mass of solid into the boat and weigh
accurately
2. Pour solid into a beaker. Reweigh empty weighing boat and calculate how much was transferred
3. Add deionised water and stir with glass rod until dissolved
4. Funnel into a volumetric flask
5. Make up to mark with deionised water until bottom of meniscus is on the mark
6. Stopper and invert to mix
(some are partly done) qualitative tests for ions and organic functional groups, a b c f h, k, volatges. -
correct answer-
Acid-Base Titration - correct answer-rinse equipment (burette with acid, pipette with alkali, conical flask
with distilled water)
•pipette 25 cm3 of alkali into conical flask
•touch surface of alkali with pipette ( to ensure correct amount is added)
•adds acid solution from burette
•make sure the jet space in the burette is filled with acid
•add a few drops of indicator and refer to colour change at end point
•phenolphthalein [pink (alkali) to colourless (acid): end point pink colour just disappears] [use if NaOH is
used] •methyl orange [yellow (alkali) to red (acid): end point orange] [use if HCl is used]
•use a white tile underneath the flask to help observe the colour change
•add acid to alkali whilst swirling the mixture and add acid drop wise at end point
•note burette reading before and after addition of acid •repeats titration until at least 2 concordant
results are obtained- two readings within 0.1 of each other
Measuring Enthalpy Change of Combustion - correct answer-1. Measure 100cm³ of water into a
calorimeter
2. Weigh the spirit burner
3. Measure initial temperature of the water
4. Clamp calorimeter above spirit burner
, 5. Light the spirit burner
6. Heat until the temperature rises by 15°C. Stir and record final temperature
7. Reweigh spirit burner
8. Calculate temperature change and heat energy change (q=mcAT)
9. Calculate mass of fuel used and moles of fuel used. Calculate energy change per mole.
Measuring Enthalpy Change of Neutralisation - correct answer-1. Place polystyrene cup in glass beaker
2. Measure out 25cm³ of 1moldm³ HCl and transfer to polystyrene cup
3. Stir and record temperature
4. Measure out 25cm³ of 1moldm³ NaOH into another measuring cylinder.
5. Add NaOH to HCl, stir and record the highest temperature reached
6. Calculate temperature change and q=mcAT
7. Calculate moles of acid used and water formed, and the enthalpy of neutralisation
Investigating Effect of Temperature on Rate of Reaction - correct answer-1. Measure out 50cm³ of
aqueous solution A and pour into a clean dry 250cm³ conical flask
2. Measure out 5cm³ of aqueous solution B and pour into test tube
3. Place conical flask on a piece of laminated paper with a cross. Add the aqueous sol b and start the
stopwatch
4. Gently stir and record initial temperature
5. Watch over the top and time how long it takes for the precipitate to form and cross to disappear
6. Note the final temperature and calculate the mean temperature using the initial and final
temperatures
7. repeat at diff temperatures???
e.g sodium thiosulfate and acid:
Na2S2O3 + 2HCl --> S + SO2 + H2O + 2NaCl
Preparing an Organic Liquid - correct answer-Heat under reflux.
Most organic liquids are flammable = water bath.
Anti-Bumping Granules - correct answer-Small, rough pieces of silica that are added to the mixture
before reflux. They provide a rough surface on which small gas bubbles can grow, avoiding bumping.
They promote smooth, even boiling. ??FINISHED HERE
Separating a Crude Product - correct answer-(fractional?) Distillation apparatus.