Practicals + Apparatus Flashcards
What is the purpose of a burette?
Measures and delivers the acid or base, drop by drop
What is the function of a volumetric pipette?
Accurately measure a fixed volume of solution to be titrated
What does a pipette filler do?
Safely draws the solution into the pipette
What are concordant titres?
Titres that are within a small range of each other, typically within 0.1 cm^3
Describe how to carry out the investigation when making salts (6 marks)
Gently heat (named acid), add (named base) in excess. Filter to remove excess (named base). Leave to crystallise in a warm place. Pat crystals dry with filter paper
In the making salts required practical, why is the acid gently heated?
To increase rate of reaction
What is the charge of anode?
-what ions does it attract?
Positive
-anions
What is the charge of cathode?
-what ions does it attract?
Negative
-cations
Why is an electrolyte used in electrolysis?
To conduct electricity
What is an electrolyte?
A molten or aqueous ionic compound
Are anodes and cathodes positively charged or negatively charged?
(Hint: PANIC)
Positive Anode
Negative Is Cathode
In electrolysis, does oxidation or reduction occur at the anode?
Oxidation at the anOde
In electrolysis, does oxidation or reduction occur at the cathode?
ReduCtion at the Cathode
What is oxidised at the anode?
-what does it form?
Non-metal anions
-forms atoms
What is reduced at the cathode?
-what does it form?
Metal cations
-form atoms
When metal cations are reduced at the cathode, what do they gain?
Gain electrons
When non-metal anions are oxidised at the anode, what do they lose?
Lose electrons
What is the cathode rule?
Lowest in reactivity series (of positive ions) forms at the cathode. The other remains in the solution
What is the anode rule?
If there are halide ions present, the diatomic halogen is produced at the anode. Otherwise, oxygen forms
When a solution of sodium sulfate, Na2SO4, is electrolysed, the products formed at the electrodes are hydrogen and oxygen. Explain the formation of the products at the electrodes. (6 marks)
H+and Na2+ go to cathode. SO4 2- and OH- go to anode. At anode, either halogen and or oxygen produced. At cathode, least reactive produced. Oxygen loses 2 electrons to form atom. Sodium gains 2 electrons to form atom
Why is electrolysis not used for metals less reactive than carbon?
It is more expensive because of a greater energy cost
