cExtra Flashcards
(99 cards)
Core practical 1
Investigate change in pH on adding powdered calcium hydroxide or oxide to a fixed volume of HCL
Method of core practical 1
Put a piece of universal indicator paper onto the white tile.
• Dip the end of the glass rod into the liquid, then tap it onto the
universal indicator paper.
• Wait 30 seconds, then match the colour to the appropriate pH on the
pH colour chart.
• Rinse the glass rod with water.
C Measure out 0.3 g of calcium hydroxide powder onto a piece of paper
or a ‘weighing boat’.
D Add the calcium hydroxide powder to the beaker, stir, then estimate
and record the pH of the mixture.
E Repeat step D seven times so that you add a total of 2.4 g of calcium
hydroxide powder to the acid.
Core practical 1 results
The pH increases rapidly at the neutralisation point
Core practical 1, what is calcium hydroxide?
Calcium hydroxide is a base. Bases can be used to neutralise acids according to the following reaction:
Core practical 1-what would that graph look like
Core practical 2
Electrolysis of copper sulphate with copper electrodes
Core practical 2, what is the method
them with emery paper. Label on of the electrodes as ‘anode’
the other as ‘cathode’
B Measure and record the mass of each electrode
C Half fill a beaker with copper sulphate solution
D Set up the circuit as shown in the diagram
Method 1 : Using copper electrodes
E Turn the power on and adjust the variable resistor to give a current
of 0.2A. Record the current. Leave the power on for 20 minutes,
adjusting the variable resistor to keep the current constant.
F Turn off the power and remove the electrodes from the beaker.
G Gently rinse the electrodes with distilled water and then dip them in
some propanone. Remove the electrodes from the propanone and
gently shake them to dry.
H Measure and record the mass of the dry electrodes
I Repeat the experiment using currents of 0.3A, 0.4A and 0.5A
Core practical 2 reaction at the anode
Cu → Cu2+ + 2e-
which is Oxidation
Core practical 2 reaction at the cathode
At the cathode: Cu2+ + 2e- → Cu which is Reduction
Core practical 2 explantation
Using copper electrodes copper is removed
from the anode and deposited on the
cathode. The mass of the anode will
decrease and the mass of the cathode will
increase.
The amount of copper transferred is proportional to the charge (the number of
electrons). This is determined by the current (I) and the time (t) for the electrolysis.
Core practical 2 graph
Core practical 2 diagram
What is core practical 3?
Investigating the electrolysis of copper sulphate using carbon electrodes
What is the method for core practical 3
A Set up the circuit as shown in the diagram opposite
B Turn on the power
C Record your observations and the name of the
product formed at each electrode.
Core practical 3 what would happen at the anode
Bubble of colourless gas, product is oxygen
Rule for competition at cathode
Least reactive metal will form
Rule for competition at anode
Halides>hydroxide>all other negative ions as the simplest non metal will form
Giant covalent
High melting point, insoluble in water and most do not conduct electricity apart from carbon as graphite
What is molecular formula
The number of atoms of each element bonded together in a simple molecule.
Explain simple molecular(covalent).
Low melting/boiling points, a few and soluble and most do not conduct electricity
What are some of the properties of ionic compounds
Form crystals due to their iregular shape
Have high melting and boiling points as the strong electrostatic forces require great deal of heat energy to break
Cannot conduct electricity when solid as the ions cannot move so they are locked in place
Can conduct electricity when they melted or dissolved in water(to give solutions)as the ions can now move and carry the charges.
What is the test for carbon dioxide?
Carbon dioxide turns limewater milky. A lighted wooden splint goes out in a test tube of carbon dioxide but this happens with other gases, too. So the limewater test is a better choice.
Litmus in alkaline
Blue
Litmus in acid
Red