Acids and Bases Flashcards
When is an acid not an acid?
• If there are no H⁺ ions present - this will happen if the compound containing hydrogen cannot dissociate.
What does polar mean and what are examples of things which are polar?
• Oppositely charged areas in a molecule, water is polar.
What are the colours of methyl orange and when is it those colours?
Methyl orange is red in acidic solutions and goes through orange to yellow in alkaline solutions.
What are the colours of litmus paper and when is it those colours?
Litmus paper is red in acidic solutions, purple in neutral solutions and blue in alkaline solutions.
What are the colours of phenolphthalein and when is it those colours?
Phenolphthalein is colourless in acidic solutions and bright pink in alkaline solutions.
Acid + Alkali/Base goes to…
Salt + Water
What do metal hydroxides and oxides react with and produce?
React with acids to produce a salt and water.
Acid + Metal goes to…
Salt + Hydrogen
What do metals above hydrogen in the Reactivity Series react with to produce?
React with dilute acids to produce salts and hydrogen gas.
Acid and Carbonate goes to…
Salt + Carbon dioxide + Water
What salt does hydrochloric acids produce?
Chloride
What salt does sulphuric acid produce?
Sulphate
What salt does nitric acid produce?
Nitrate
What salt does phosphoric acid produce?
Phosphate
How does one name a salt?
- First part - metal present.
* Second part - parent acid.
What is the definition of an acid?
- Acids are a source of hydrogen ions.
* Acids donate hydrogen ions.
What nitrates are soluble?
All nitrates are soluble
What chlorides are soluble?
All chlorides are soluble except silver chloride.
What sulphates are soluble?
All sulphates are soluble except barium sulphate and calcium sulphate.
What carbonates are soluble?
Most carbonates are insoluble, except for sodium, potassium and ammonium carbonates.
What hydroxides and oxides are soluble?
All hydroxides and oxides are insoluble expect potassium, sodium and ammonium.
Which bases are insoluble?
Most metal oxides, metal carbonates and metal hydroxides are insoluble.
What is the method to make soluble salts from acids?
- Add excess of an insoluble base to an acid and mix them together.
- Filter off the unused solid.
- Heat the solution to evaporate the water.
- Leave the solution to form of the salt crystals.
- Pour off any uncrystallised solution.
- Blot crystals dry with paper tissue.
Why do crystals form when magnesium sulphate is cool?
Solubility decreases with temperature, causing crystals when it’s cool and the solubility changes.
Why do we not heat magnesium sulphate until it’s dry?
We want to make hydrates magnesium sulphate, but if it’s heated until all the water is gone it would be anhydrous magnesium sulphate.
What is the equation for the making of magnesium sulphate?
- sulphuric acid + magnesium -> magnesium sulphate + hydrogen
- H₂SO₄(aq) + Mg(s) -> MgSO₄(aq) + H₂(g)
What is the method to make an insoluble salt (precipitation reaction)?
- Mix two soluble salt solutions together.
- Filter the mixture through filter paper.
- Wash the solid precipitate with water.
- Leave it in a warm place to dry.
How do ionic equations work?
Ba₍aq₎²⁺ + SO₄₍aq₎²⁻ –>
BaSO₄₍s₎
Explain, with reference to protons, why a reaction would be a neutralisation reaction.
An acid would provide protons and the products would be neutral therefore.
Why would blue litmus turn red when added to a solution?
The solution would be acidic and there would be hydrogen ions present.
Why would blue litmus stay blue when added to a solution?
The solution would not have any hydrogen ions present and would not be acidic.
How do you make a sodium, potassium or ammonium salt? (6)
- Add a measured volume of alkaline solution to a flask using a pipette/measuring cylinder.
- Add a named indicator (e.g. methyl orange).
- Add acid from a burette until a correctly stated colour change (e.g. turns orange).
- Note the volume of acid added.
- Mix the same volume of acid and alkaline solution without the indicator.
How do you convert from mol/dm³ into g/dm³?
concentration is 0.6 dm³
mass = moles x RFM = 0.6 x 58.5 = 35.1 concentration = mass ÷ volume = 35.1 ÷ 1 = 35.1g/dm³
What is an alkali?
A source of hydroxide ions.
