Chemistry B Flashcards
What is an exothermic reaction?
Transfers energy to surroundings e.g. neutralization
What is an endothermic reaction?
Takes energy from surroundings e.g. thermal decomposition.
What reaction occurs when an acid and alkali react together?
Exothermic reaction
What ions are always found in an acid?
Hydrogen (H+)
What ions are always found in an alkali?
OH-
What factors affect rate of reaction?
Temperature, concentration and surface area
What is the collision theory?
Particles must collide with sufficient energy. Amount of energy particles must have for reaction is activation energy. Must increase number of successful collisions.
What is a catalyst?
A substance that increases rate of reaction, without being involved or used up in the chemical reaction.
How can a solid be separated from a solution?
Filtering
What is it called when two solutions are mixed?
Precipitate
What happens in terms of ions and molecules when when an acid reacts with any alkali?
Hydrogen ions (from acid) reacts with hydrroxide ions (from alkali) to produce water. H+ + OH- = H2O
What could you do to a solid to make it conduct electricity?
Melt it
During electrolysis why do positive ions go to negative electrodes?
Because positives attract
What do the ions turn into when they reach the negative electrode?
Atoms
What is electroplating?
Coating a cheap metal with a thin layer of expensive metal.
Why might the electrolyte contain cryolite?
Because it lowers melting point therefore less energy is needed to melt it.
What is meant by electrolysis?
Decomposition and produces chemical reactions using elements.
What can Soluble salts be made from by using acids to react them with?
Metals, insoluble bases and alkalis
How are insoluble salts made?
By mixing appropriate solutions of ions so that a precipitate is formed. Precipitation can be used to remove unwanted ions from solutions.
What is an anode?
Positive electrode
What is a cathode?
Negative electrode
What is an electrolyte?
A substance that you carry electrolysis on.
What are electrodes?
Conductors that electricity enters or leaves an object.
What is the first stage of electrolysis?
Apply heat to beaker to melt electrolyte to break down ions in compound.
What is the second stage of electrolysis?
There will be a + and - electrode. Ions are free to move as compound has been melted.
What is the third stage of electrolysis?
+ ions attracted to - electrode and - ions attracted to + electrode.
What is the fourth stage of electrolysis?
Ions must be turned into atoms so electrons flow through electrode to balance out ions so they become an atom. + ions lose electrons and - ions gain electrons.
Whats the problem if the compound is dissolved instead of melted during electrolysis?
OH- and H+ ions will be there and be attracted to the electrodes too.
