Chemistry C3 Flashcards
Redox Reactions, Acids and Alkalis, Electrolysis
What is the term for the loss of electrons or the gain of oxygen?
Oxidation
What is the term for the gain of electrons or the loss of oxygen?
Reduction
What are reducing and oxidising agents?
An oxidizing agent is a substance that causes oxidation by accepting electrons; therefore, it gets reduced. A reducing agent is a substance that causes reduction by losing electrons; therefore it gets oxidized.
What is electrolysis?
Electrolysis is a technique that uses direct electric current to drive an otherwise non-spontaneous chemical reaction.
What is the solution used to decompose the substance being dissolved in it?
Electrolyte
Name the two electrodes?
Anode - The positive electrode
Cathode - The negative electrode
Where do redox reactions occur in electrolysis?
Oxidation occurs at the positive electrode as the ion loses electrons while reduction occurs at he negative electrode as the ions gains electrons.
Why are dissolved ionic substances able to conduct electricity?
They are able to conduct electricity as they are decomposed from the electrolyte solution meaning ions are free to move which allows them to conduct electricity.
What are acids?
A substance that releases H+ ions when dissolved in water
What are alkalis?
A substance that releases OH- ions when dissolved in water.
What are bases?
A substance that reacts with an acid to produce a salt and water.
Acid + Base –>
Salt + Water
Acid + Carbonate –>
Salt + Water + Carbon Dioxide
Acid + Metal –>
Salt + Hydrogen
Property of strong acids?
Completely dissociates in water
Property of weak acids?
Partially dissociates in water
Why do concentrated acids have a low pH?
They have a high concentration of H+ ions per litre
Why do dilute acids have a high pH?
They a low concentration of H+ ions per litre
What are the products of an electrolyte that is a solution?
OH-, H+, The Non-Metal Ion, The Metal Ion
What are the key points of metals in solutions?
Metals that are more reactive than hydrogen will cause hydrogen to form from electrolysis of hydrogen ions when electrolysed in solution.
What are the key points of ions in solutions?
Ions that aren’t halide ions will cause hydroxide ions to be electrolysed instead, and produce oxygen. The reaction that you need to remember is:
4OH- –> 2H2O + O2 + 4e-
What is electroplating?
Electroplating is a process for producing a metal coating on a solid substrate through the reduction of cations of that metal by means of a direct electric current.
What happens to the bonds during an
endothermic reaction?
In endothermic reactions, the energy needed to break existing bonds is greater than the energy released when new bonds are formed so there is a higher amount of energy in the products than the reactants.
What happens to the bonds during an exothermic reaction?
In an exothermic reaction, the energy released when new bonds are formed is greater than the energy taken in breaking the existing bonds so there is a higher amount of energy in the reactants than the products.
