Acids, Bases & Salts Flashcards
What is produced when an acid reacts with a metal?
When an acid reacts with a metal, it produces a salt and hydrogen gas.
What is an alkali?
An alkali is a water-soluble base.
What colour does litmus paper turn in acidic conditions?
In acidic conditions, litmus paper turns red.
Why is litmus not suitable for titrations?
Litmus is not suitable for titrations because its color change is not sharp and it goes through a purple transition color in neutral solutions.
What is an indicator?
An indicator is a substance that changes colour in acidic or alkaline conditions, used to determine the pH of a solution.
Define the term neutralisation.
A neutralisation reaction is a reaction between an acid and a base to form a salt and water.
Name the products formed from the reaction between sodium hydroxide and hydrochloric acid.
The products formed from the reaction between sodium hydroxide and hydrochloric acid are sodium chloride and water.
What is the general equation for the reaction of a metal carbonate with an acid?
metal carbonate + acid ⟶ salt + carbon dioxide + water
What determines the identity of the salt produced in an acid-base neutralisation reaction?
The identity of the salt produced depends on the acid used and the positive ions in the base.
What substances act as bases in acid-base reactions?
Metal oxides, metal hydroxides and metal carbonates act as bases in acid-base reactions.
Which ions causes a substance to be acidic?
The ion that causes a substance to be acidic is a hydrogen ion / H+.
Which ions causes a substance to be alkaline?
The ion that causes a substance to be alkaline is a hydroxide ion / OH-.
What pH is classed as neutral?
pH 7 is classed as neutral.
What pH range is classed as alkaline?
The pH range for alkaline is 8-14.
What pH range is classed as acidic?
The pH range for an acid is 0-6.
What is the pH of distilled water?
The pH of distilled water is 7.
Describe how to use universal indicator to test the pH of a substance.
Add a few drops of universal indicator solution to the substance.
Check the colour against a colour chart to determine the pH value.
What is a proton donor?
A proton donor is an acid that ionises in solution producing protons (H+ ions).
What is a proton acceptor?
A proton acceptor is a base that accepts protons donated by an acid.
Define strong acid.
A strong acid is an acid that completely dissociates (or ionises) in water, producing solutions of a very low pH.
Define weak acid.
A weak acid is an acid that partially dissociates (or ionises) in water, producing pH values closer to the middle of the pH scale, while still being below 7.
What is an example of a weak acid?
propanoic acid
Define concentrated solution.
A concentrated solution is a solution that contains a higher number of solute molecules per dm3 of solution.
What is an oxide?
An oxide is a compound made from one or more atoms of oxygen combined with one other element.
What is an acidic oxide?
An acidic oxide is an oxide formed when a non-metal element combines with oxygen, reacting with bases to form a salt and water.
What is a basic oxide?
A basic oxide is an oxide formed when a metal element combines with oxygen, reacting with acids to form a salt and water.
What type of solution do acidic oxides produce when dissolved in water?
Acidic oxides produce an acidic solution with a low pH when dissolved in water.
What type of solution do basic oxides produce when dissolved in water?
Basic oxides produce a basic solution with a high pH when dissolved in water.
What is an amphoteric oxide?
An amphoteric oxide is an oxide that can behave as both acidic and basic, depending on whether the other reactant is an acid or a base.
Give two examples of amphoteric oxides.
Two examples of amphoteric oxides are zinc oxide (ZnO) and aluminium oxide (Al2O3).
Why is the insoluble base added in excess during the preparation of a soluble salt?
The insoluble base is added in excess to ensure that all of the acid has reacted.
What step is taken to remove the excess insoluble base after the reaction?
The excess insoluble base is removed by filtration.
What is left in the solution after the excess base is removed?
After removing the excess base, only the salt and water remain in the solution.
Define the term insoluble base.
An insoluble base is a base that does not dissolve in water.
How are crystals produced from a salt solution?
The solution is heated gently and then left to cool.
Name the method used to prepare a soluble salt from an acid and alkali.
The method used to prepare a soluble salt from an acid and alkali is titration.
Why is an indicator used during the preparation of a soluble salt by titration?
An indicator will indicate when neutralisation has occured.
Define precipitation reaction.
A precipitation reaction is a reaction where an insoluble solid (precipitate) is formed from two soluble reactants
What is meant by a precipitate?
A precipitate is an insoluble solid that is formed from a reaction between two soluble reactants.
Why is the precipitate washed with distilled water?
The precipitate is washed with distilled water to remove traces of the solutions it was made from.
Give three examples of insoluble sulfates.
barium sulfate
calcium sulfate
lead(II) sulfate
Give an example of a soluble hydroxide.
sodium hydroxide
potassium hydroxide
calcium hydroxide
Define a hydrated substance.
A hydrated substance is one which is chemically combined with water.
Define an anhydrous substance.
An anhydrous substance is a substance containing no water.
Define water of crystallisation.
Water of crystallisation refers to the water molecules present in a hydrated substance.
