Answering Paper 3 Questions - Share and discuss

Answering Paper 3 Experiment

Problem statement
•   How MV affect RV?
•   Must MV follow by RV
•   Must have question mark’?’
•   Ex: How does the (position of Group 1 elements) affect the (reactivity with water)?
•   Ex: How does the (concentration of an acid) affect the (pH value of the acid)?
•   Ex: How does the (distance between two different metals) in ECS affect the (potential different) in a voltaic cell?
•   Ex: How do (different metals in contact with iron nail) affect (the rusting process)?

Hypothesis
(MV + RV) + Direction
•   The lower the (position of Group 1 metal), the higher the (reactivity of the metal) reacts with water.
•   The higher the (concentration of an acid), the lower the (pH value of an acid).
•   The further the (distance between two metals) in electrochemical series, the higher the (potential difference/voltage) produced in a chemical cell.
•   The more electropositive (metal when in contact with iron nail) will inhibit (rusting) but the less electropositive (metal when in contact with iron) will speed up (rusting).

Diagram – no mark but helps to score materials/apparatus and procedure

Procedure
As complete as possible, do not start with ‘set up as shown in the diagram’

Tabulation of data
Draw table and put in your MV and RV

Group 1 elements(MV)   Reactivity with water(RV)
Li
Na
K

Operational Definition
•   How to operate the experiment + Observation + Inference
•   When a piece of alkali metal is placed on the surface of water, the more vigorous it moves on water, the more reactive the metal is.
•   When a pH meter is dipped into an acid, the lower pH values indicate the higher concentration of hydrogen ions present in the acid.
•   When two different metals are dipped into an electrolyte, the higher the voltage produced in a cell indicates the distance between two metals in the ECS is further away.
•   When a less electropositive metal pairs with iron nail, the dark blue precipitate formed in the jelly solution. This indicates the rusting process occurs.

MV How to manipulate
Group 1 metals    (How you manipulate the Group 1 metals?)
             Use Li, Na, K to react with water in each repeated experiment

RV What to measure/observe
Reactivity of metal    (What do you observe that allow you to know the reactivity of metal with water?)
               How metals move on surface of water

CV/FV What to be maintained
Water, size of metal    (how do you maintain the use of water and size of metal?)
                 Use water to react with alkali metal in each reaction
   Use same size of metal to react with water in each reaction

Observation
•   What you see, hear, feel…
•   Potassium burns with bright lilac flame and produced ‘pop’ sound
•   The red litmus paper turn blue (before and after) + object
•   The blue colour copper (II) sulphate becomes paler (before and after) + object

Inference
•   Explain what you see
•   (Dark blue spot) indicates the presence of Fe²⁺/rusting occurs
•   (High voltage value) indicates the distance between two metals in ECS is further away from each other
•   (Blue litmus paper remains blue) because without water, the glacial ethanoic acid cannot shows its acidic properties.