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CC8H SC8H
Pearson GCSE Combined and Separate Science Chemistry Higher
Question | Answer |
---|---|
Define an acidic solution in terms of ions | A solution which contains an excess of Hydrogen (H+) ions. |
Define an alkaline solution in terms of ions | A solution which contains an excess of Hydroxide (OH-) ions. |
Define a neutral solution in terms of ions | A solution which contains an equal number of H+ and OH- ions. |
What is an indicator? | A substance that turns a different colour in an acidic solution compared to its colour in alkaline solution. |
What colour is phenolphthalein in acid and alkaline solution? | Colourless in acid, Pink in alkali. |
What colour is litmus in acid and alkaline solution? | Red in acid, Blue in alkali. |
What colour is methyl orange in acid and alkaline solution? | Red in acid, Yellow in alkali. |
State the formulae of hydrochloric, sulfuric and nitric acids | HCl, H2SO4, HNO3. |
What is a strong acid? | An acid which completely splits up into its ions in water Eg All HCl molecules split up into H+ and Cl- ions. |
What is a weak acid? | An acid which will have some molecules which do not split up into their ions EG in ethanoic acid only some of the molecules will have split into the ethanoate ion and H+ ions. |
How does the pH depend on the concentration of H+ ions in solution, | As the concentration of H+ increases by a factor of x10, the pH decreases by 1. |
What is a concentrated acid | An acid where there are a large number lots of acid molecules in a litre of water. |
What is a dilute acid? | An acid where there are a small number lots of acid molecules in a litre of water. |
A base is a compound that can neutralise acid. Name the three types of base | Metal Oxide, Metal Hydroxide, Metal Carbonate. |
What is a neutralisation reaction | A reaction that involves an acid A salt is always produced in a neutralisation reaction. |
What is a salt? | A compound formed when some or all of the hydrogen ions in an acidic solution are replaced by metal ions. |
State the names of the salts produced by hydrochloric, sulfuric and nitric acids | Hydrochloric acid = Chlorides, Sulfuric acid= Sulfates, Nitric Acid = Nitrates. |
Write the equation showing the reaction between H+ and OH- ions | H+ + OH- →H2O. |
Complete the general equation metal + acid → | Salt + Hydrogen gas. |
Write a chemical equation for magnesium reacting with sulfuric acid | Mg + H2SO4 →MgSO4 + H2. |
Complete the general equation metal oxide + acid → | Salt + water. |
Write a chemical equation for copper oxide reacting with nitric acid | CuO + 2HNO3 → Cu(NO3)2 + H2O. |
Complete the general equationmetal hydroxide + acid → | Salt + water. |
Write a chemical equation for sodium hydroxide reacting with hydrochloric acid | NaOH + HCl → NaCl + H2O. |
Complete the general equation metal carbonate + acid → | Salt + Water + Carbon Dioxide. |
Write an ionic equation for the reaction of hydrochloric acid with sodium carbonate solution | CO32-(aq) + 2H+(aq) → H2O(l) + CO2(g). |
What are the two methods by which we can measure the pH of a solution? | Use universal indicator and compare the colour the indicator turns to a colour chart, use a pH probe. |
If a salt is in solution how do you extract it as a solid? | Allow the water to evaporate and it will leave the salt behind as a solid (crystallisation). |
When we produce copper sulfate by reacting copper oxide with sulfuric acid how do remove the excess, unreacted copper oxide? | Filtration. |
Name the salts which are always soluble | Sodium, potassium, ammonium salts and nitrates. |
Name the only two insoluble chlorides | Silver Chloride and Lead Chloride. |
Name the only three insoluble sulfates | Lead Sulfate, Barium Sulfate, Calcium Sulfate. |
Name the two salts that are mostly insoluble | Carbonates and Hydroxides. |
What do we call an insoluble solid produced by the reaction of two aqueous solutions? | A precipitate. |
How do we produce a pure dry sample of an insoluble solid produced by the reaction of two aqueous solutions? Write the three stages | Filter, Wash the residue with distilled water, Dry in an oven. |
Write a balanced equation with state symbols for the reaction of silver nitrate AgNO3 solution with Sodium Chloride NaCl solution | AgNO3(aq) + NaCl(aq) → AgCl(s) + NaNO3(aq). |
Write an ionic equation with state symbols for the formation of a solid silver bromide by reacting silver nitrate solution (AgNO3) with potassium chloride solution (KBr) | Ag+(aq) + Br-(aq) → AgBr(s). |
What does soluble mean? What does insoluble mean? | Dissolves in water, Does not dissolve in water. |
Define acid in terms of pH | A substance with a pH of less than 7. |
Define acids in terms of ions | A substance which releases H⁺ ions in solution. |
State the three common acids and give their formulae | Hydrochloric acid, HCl(aq), Sulphuric acid, H₂SO₄(aq), Nitric acid, HNO₃. |
Which ions do the common acids form in solution? | HCl forms H⁺ and Cl⁻, H₂SO₄ forms 2H⁺ and SO₄²⁻, HNO₃ forms H⁺ and NO₃⁻. |
What is a neutral solution? | A solution with a pH of 7Water is an example. |
How do you measure pH? | With an indicator or pH probe. |
What is a base? | A metal oxide, hydroxide or carbonate that will react with an acid, Eg copper oxide. |
What is an alkali? | A soluble base, Eg sodium hydroxide. |
Which ions are always present in a solution of an alkali? | OH⁻. |
What is a salt? | A compound formed when some or all of the hydrogen from an acid is replaced by a metal, Eg CuSO₄, copper sulphate, where copper has replaced H from H₂SO₄. |
What type of salts are formed by the three main acids? | Hydrochloric acid produces chlorides, sulphuric acid = sulphates, nitric acid = nitrates. |
What is a neutralisation reaction? Write an ionic equation for neutralisation | A reaction involving an acid that results in a neutral solution H⁺ + OH⁻ → H₂O. |
Which ions always react together in a neutralization reactions between acids and alkalis? | H⁺ and OH⁻. |
metal + acid → | → salt + hydrogen gas. |
metal hydroxide + acid → | → salt + water. |
metal oxide + acid → | → salt + water. |
metal carbonate + acid → | → salt + water + carbon dioxide. |
How do you make a soluble salt from an acid? | React the acid with a base , Eg to make copper sulphate react copper oxide with sulphuric acid. |
If a salt is in solution, how do you extract it as a solid? | Allow the water to evaporate off and it will leave the salt behind as a solid. |
What is a strong acid? | An acid which completely splits up into its ions in water, Eg when HCl is in water all the HCl molecules split up into H⁺ and Cl⁻. |
What is a weak acid? | An acid which will have some molecules which do not split up into their ions, Eg in ethanoic acid only some of the molecules will have split up into the ethanoate ion and H⁺ ions. |
What is the relationship between an acid of pH2 and an acid of pH 3? | pH 2 is 10 times more hydrogen ions than pH 3. |
What is a concentrated acid? | An acid where there are lots of acid particles in the water. |
What is a dilute acid? | An acid where there are fewer acid particles in the water. |
How is pH measured? | pH is related to the concentration of H⁺ in a solution. |
How can hydrogen be tested for? | Makes a squeaky pop when a splint is placed in it. |
How can carbon dioxide be tested for? | Bubble through limewater, turns it milky (cloudy). |
What colour is litmus in acid and alkali? | Acid – red, alkali – blue. |
What colour is methyl orange in acid and alkali? | Acid – red, alkali – yellow. |
What colour is phenolphthalein in acid and alkali? | Acid – colourless, alkali – pink. |
How do you prepare a sample of a soluble salt from a base and an acid? | Neutralisation, filtration, crystallisation. |
How do you prepare a sample of a soluble salt from an acid and an alkali? | Titration, repeat titration without indicator, crystallisation. |
How do you prepare a sample of an insoluble salt from two solutions | Combine, filtration. |
Soluble or insoluble? nitrates | Soluble. |
Soluble or insoluble? Sodium salts | Soluble. |
Soluble or insoluble? Chloride salts | Soluble, except silver and lead compounds. |
Soluble or insoluble? sulphates | Soluble, except lead, barium and calcium compounds. |
Soluble or insoluble? carbonates | Insoluble, except sodium, potassium and ammonium. |
Soluble or insoluble? hydroxides | Insoluble, except sodium, potassium and ammonium. |