Module 2 - chapter 4 Flashcards
What is the definition of an acid?
A proton donor
Why does the state of an acid change whether it is an acid or not?
The hydrogen ions (protons) must be free to move in solution, so the acid has to dissolve in water
What is the formula of phosphoric acid?
H3PO4
What is the formula of ethanoic acid?
CH3COOH
What is a strong acid?
An acid which releases all of its hydrogen ions into solution and completely dissociates in aqueous solution
What is a weak acid?
An acid which only releases a small proportion of its available hydrogen ions into solution, partially dissociates in aqueous solution,
What is an important feature of an equation showing a weak acid?
The equilibrium sign to show that the forward reaction is incomplete because the ionisation is a reversible reaction
Are organic acids mostly strong or weak?
Weak, e.g. ethanoic acid is weak
What class as bases?
Metal oxides, metal hydroxides, metal carbonates and ammonia
What is pH a measure of?
Hydrogen ion concentration:
High H+ concentration = low pH
Low H+ concentration = high pH
Do strong or weak acids react faster? Why?
Strong acids react faster because all H+ ions available to react at once so gives a faster reaction
What happens to the equilibrium of the reaction when weak acids react?
The equilibrium shifts to the right because the H+ are being used up, this gives a slower reaction
What is he definition of a base?
A proton acceptor
What is an alkali?
A soluble base that releases OH- in an aqueous solution
What is a salt?
A salt is formed when an acid has one or more of its hydrogen ions replaced by either a metal ion or an ammonium ion.
What happens in neutralisation?
In neutralisation of an acid, H+ ions react with a bee to form a salt and water. The H+ ions are replaced by metal or ammonium ions from the base.
What is oxidation number?
The number of electrons involved in bonding to a different element
What do ionic equations include?
Everything but with the spectator ions removed
What do half equations include?
Only the ions and the electrons added/removed
If oxidation number increases, what has happened to the number of electrons?
The number of electrons has decreased as electrons are lost, the element becomes more positive
If oxidation number decreases, what has happened to the number of electrons?
The number of electrons has increased as electrons are gained, the element becomes more negative
What is the reducing agent?
The chemical which has been oxidised
What is the oxidising agent?
The chemical which has been reduced
What makes a good reducing agent?
An element which can readily lose electrons
