Please enable JavaScript.

Coggle requires JavaScript to display documents.

Chemistry chapter 8: Acids and Bases - Coggle Diagram

- - - - the acid when reacted with reactive metals, form a salt and hydrogen gas there are three main types of salts:
        sulfates when formed with sulfuric acid
        nitrates when formed with nitrate acid
        chlorides when formed with hydrochloric aicd
        
        to test if hydrogen is given out, place a lighted splint at the mouth of the test tube, hydrogen gas extinguishes the burning splint with a 'pop' sound
      - not all metals react with acids to produce a salt and hydrogen gas thus nothing happens, lead appears not to react with hydrochloric acid and sulfuric acid, the initial reaction produces a layer of lead(II) chloride or lead(II) sulfate, which is insoluble in water and quickly forms a coating around the metal, protecting it from further reaction with the acid
      - there are 5 types of reactions with acids and bases
        
        acid + carbonate produces salt, water, carbon dioxide
        
        base + ammonium salt produces salt, water, ammonia
        
        acid + reactive metal produces salt and hydrogen
        
        alkali + aqueous salt produces salt and in soluble hydroxide
        
        acid + base (neutralisation) produces a salt and water
        
        SALTS PRODUCED ARE VARIABLE, everything else is fixed, the INSOLUBLE HYDROXIDE IS VARIABLE
- - - - basic oxides like sodium oxide Na2O, magnesium oxide MgO, copper(II) oxide CuO, reacts with acids to form salts, the vast majority of metal oxides, mostly insoluble, all metal oxides and hydroxides are insoluble, except for Group1 oxides and hydroxides, few oxides dissolve in water to form alkalis
      - amphoteric oxides, reacts with BOTH ACIDS AND BASES to form salts, like Zinc oxide ZnO, aluminium oxide, Al2O3, lead(II) oxide, PbO, these 3 are insoluble in water, all metal oxides and hydroxides are insoluble except for Group1 oxides and hydroxides
    - - acidic oxides like carbon dioxide CO2, sulfur dioxide SO2, nitrogen dioxide NO2, react with bases to form salts, vast majority of non-metal oxides, reacts with bases to form salts
      - neutral oxides, like water H2O, nitric oxide NO, carbon monoxide CO, do not react with acids or bases
- - - - weak acids, will turn universal indicator orange/yellow, where the pH level is 4-6
      - neutral solutions turn universal indicator green, pH level is 7
      - strong acids will let the universal indicator turn red, where the pH level is 1-3
      - weak alkali, turn universal indicator blue with a pH level of 8-11
      - strong alkali turn universal indicator violet where the pH level is 12-14
      - there are 2 other indicators used to tell acidity of a solution
        
        methyl orange, turns red if pH is less than 3.5 , turns blue if pH is more than 4.1, if solution is neutral, range is 3.5<x<4.1
        
        litmus paper, turns red if pH is less than 7, turns blue if pH is more than 7, however, no change will be observed if pH is 7; red litmus will remain red, blue litmus remain blue
- - - - sulfur dioxide SO2, from combustion of sulfur-containing fossil fuels, in power stations and motor vehicles
        
        damages lungs, causing bronchitis, combine with water in the atmosphere to form strong acids like sulfuric and nitric acid, causes formation of acid rain which damages anything made of metal and stone, and also ,lowers pH of water and soil, killing aquatic life and trees
        
        to minimise, remove sulfur from fossil fuels before they are burnt, remove SO2 from waste gases formed when sulfur-containing fuels undergo combustion, called flue gas desulphurisation, calcium carbonate is used for this
        
        to minimise, fit cars with catalytic converters that convert 2NO + 2CO -> N2 + 2CO2
        
        to treat excessive acids in soils, bases like quicklime CaO/ slaked lime Ca(OH)2 can be used, should not be added with nitrogenous fertilisers, ammonium salts + base -> ammonia gas escapes into the atmosphere, rendering fertiliser ineffective, should alternate cycle between fertilising soil and de-acidifying the soil in each planting cycle
        
        in acidic lakes, CaO/Ca(OH)2 can be used to 'lime' lakes although limestone CaCO3 may be preferrable, CaCO3 is insoluble in zh2O, thus removing acid and excess limestone remaining undissolved, CaO/Ca(OH)2 used to render the water alkaline
      - oxides of nitrogen NOx, produced by car engines, under high temperatures, it combines to form NO which then converts to NO2 by reacting with oxygen