C5 - Chemical Changes

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Cards (23)

What is Oxidation?
Substance gains oxygen
Substance loses electrons
What is Reduction?
Substance loses oxygen
Substance gains electrons
What are the trends in reactivities of metals in reactions with acid/water
Metals above H² in the reactivity series react with acids to produce H². The more reactive the metal is, the quicker and more violent the reaction with the acid occurs
Not all Metals above H² react with water - Mostly Group 1 and II Metals. Aluminum is the bordeline case.
Metals below H² don't react with acids
What is a displacement reaction?
a reaction where a more reactive metal displaces a less reactive metal from a compound
How can metals less reactive than carbon be extracted?
Reduction with carbon. Carbon displaces the metal in a metal oxide - gets oxidised to carbon dioxides.
Metal fom the metal oxide gets reduced to the pure metal.
General Equation for reaction between metals and acids
metal + acid -> salt + hydrogen
Redox and Displacement Reaction
Which mets in the reactivity series will react with acid?
Those above hydrogen
General Equation for a neutralisation reaction
Base + Acid -> Salt + Water
General equation for the reaction between metal carbonate and acid
Metal Carbonate + Acid -> Salt + Water + Carbon Dioxide
General equation between metal oxides and acids
Metal Oxide + Acid -> Salt + Water
What is a Redox Reaction
Reaction where both oxidation and reduction occurs
How is a soluble salt formed?
React with the excess acid with some insoluble chemical (e.g metal oxide)
Filter off leftovers
Crystalise the product
What ions do acids and alkalis producd in aqueous solutions?
Acids
Hydrogen Ions H+
Alkalis
Hydroxide Ions OH-
What is a strong acid?
An acid that is completely ionised in aqueous solution
What is a weak acid?
An acid that is only partially ionised in aqueous solution
What happens to pH as concentration of H+ increases?
pH decreases
What is a concentrated acid?
More moles of acid per unit volume than dilute
Not the same as strength of an acid
As the pH is decreased by one unit, what change is seen in the hydrogen ion concentration?
Increases by a factor of 10
Name the following salts:
LiNO³ - Lithium nitrate
K²CO³ - Potassium Carbonate
MgBr² - Magnesium Bromide
BaSO⁴ - Barium Sulfate
What is an Ionic equation?
gives some substances as ions and has spectator ions removed
What is a spectator ion?
ion fhat is unchanged in a reaction
What is a half equation?
Equation that shows whether a substance is losing or gaining electrons
What is a neutralisation reaction?
a reaction between an acid and base to produce water