Topic 4 Flashcards
What does acid + metal carbonate make?
acid + metal carbonate -> salt + water + carbon dioxide
What does acid + metal hydrogen carbonate make?
acid + metal hydrogen carbonate -> salt + water + carbon dioxide
What does acid + metal hydroxide make?
acid + metal hydroxide -> salt + water
What does acid + metal oxide make?
Acid + metal oxide -> salt + water
What does acid + metal make?
acid + metal -> salt + hydrogen
What does soluble acid and soluble base make?
soluble acid + soluble base -> soluble salt + water
What is the ion of hydrogen carbonate?
(HCO3)-
What is an alkali?
Soluble base
What is the procedure to get a salt from soluble acid and soluble base reaction?
Procedure: Neutralisation by titration. It uses a known concentration of a soluble acid, which is neutralised by an alkali. It forms a salt solution that is dissolved in water.
Purification: Evaporation. Since a salt solution is produced the salt needs to be isolated. This is done by evaporation to remove most of the water. The crystalline salt can be dried on paper or left in a warm oven
What does a soluble acid and insoluble base make?
Soluble acid + insoluble base -> soluble salt + water + (carbon dioxide)
What is the procedure to get a salt from soluble acid and insoluble base reaction?
Procedure: Neutralisation. Add excess insoluble base/carbonate so that all acid fully reacts. Forms a salt solution (dissolved in water). Can do titration aswell.
Purification: Filtration and evaporation. Filtering the final solution removes any unreacted solid bases and evaporation is done to isolate the salt.
What is water of crystallisation?
A crystalline salt that is hydrated or chemically combined with water
What is an anhydrous salt?
A salt that is heated to complete dryness. A compound with all water molecules removed
How to find the amount of water associated with a salt experimentally?
- An accurate mass of hydrated salt is heated in a crucible to drive off all the water present
- The mass of the heated salt is recorded
- The salt is heated again until constant mass is obtained. This is now the anhydrous salt
Calculation: mass of hydrated salt - mass of anhydrous salt = mass of water
What does a soluble salt + soluble salt make?
Soluble salt + soluble salt -> insoluble salt + soluble salt
What is the procedure to get a salt from a reaction between two soluble salts?
Procedure: Precipitation. When two ionic salts are combined, they can form an insoluble salt; a precipitate.
Purification: Filtration. Filtering a mixture separates the insoluble salt as the precipitate
Purification: Washing and drying. Washing the precipitate to remove soluble impurities. Oven drying to obtain dry salt
If there is a reaction between two soluble salts AB and CD, what will the products be and which will be soluble and insoluble?
AB + CD -> AD (soluble) + BC (insoluble)
4 common acids
Hydrochloric acid (HCl)
Sulfuric acid (H2SO4)
Nitric acid (HNO3)
Ethanoic acid (CH3COOH)
4 common bases
Sodium hydroxide (NaOH)
Potassium hydroxide (KOH)
Sodium carbonate (Na2CO3)
Calcium carbonate (CaCO3)
What compounds are soluble?
Group 1 and NH4+(ammonium)
Are nitrates soluble?
All nitrates are soluble
Are carbonates soluble?
All carbonates are insoluble except those of group 1 and (NH4)2CO3
Are chlorides soluble?
All chlorides are soluble except AgCl and PbCl2
Are sulphates soluble?
All sulphates are soluble except CaSO4, PbSO4 and BaSO4
Are hydroxides soluble?
All hydroxides are insoluble except for those of group 1 and group 2 are slightly soluble
Characteristics of acids
- strong acids are corrosive
- weak acids taste sour
- acids turn litmus paper red
- pH below 7
- acids contain hydrogen (however not all things with hydrogen are acidic)
- acids react with alkaline
Characteristics of bases
- can be used as soaps and cleaning solutions
- turn litmus paper blue, turns universal indicator dark green, blue and purple
- react with acids
- pH above 7
- corrosive
What is a hydrogen ion?
A proton
What is an acid?
A proton donor
What happens to an acid when added to water?
Disassociates (split up) into H+ ions and negative ions (anions)
Why must an acid have hydrogen?
To donate a proton
What is a base?
A proton accepter
What do bases do when added to water?
Disassociate (split up) into OH- ions and positive metal ions (cations)
What is the net ionic equation for all acid and base neutralisation?
OH- + H+ -> H2O
What happens to a strong acid in water?
Fully disassociates in water to H+ ions. All H+ ions are donated and separate from the anions
What happens to a weak acid in water?
Partially disassociates in water into H+ ions. Some H+ ions are donated and the system forms an equilibrium
When do ammonium salts decompose?
When mixed with a strong base
Equation for ammonium salt
ammonium salt -> salt + water + ammonia gas (NH3)
Describe the stages in the preperation of a sample of dry copper sulfate crystals using sulfuric acid and copper oxide. Include a balanced equation. (7)
- React excess copper oxide with sulfuric acid
- Stir and heat mixture in a conical flask
- Filter excess black solid (copper oxide)
- Concentrate solution by heating in an evaporating basin
- Leave to stand and cool slowly to form crystals
- Dry crystals between filter papers/in oven
H2SO4 (aq) + CuO(s) -> CuSO4(aq) + H2O(l)
What are most non-metal oxides?
Acidic
What are most metal oxides?
Basic
What is amphoteric?
Some species are able to react like an acid and a base. Aluminium hydroxide is an example when it reacts with HCl it is a base and when it reacts with NaOH it is an acid.
What is amphiprotic?
Some species are able to donate and accept protons. Water is an example as it can accept a proton to be H3O+ or lose an electron to be OH-
What’s the easiest way to test oxide?
To observe a reaction
What do acidic and amphoteric oxides react with metal carbonates to form?
carbon dioxide gas
What do acidic oxides do?
Dissolve in water and lower the pH (test with universal indicator)
What do basic and amphoteric oxides do?
React with acids and be neutralised
What is limewater?
Name for a saturated aqueous solution of calcium hydroxide Ca(OH)2