4.9 Describe experiments to carry out acid-alkali titrations

Ignore the flea in the diagram above (not sure what it is....)

• Prepare the apparatus above
• Fill the burette with a known volume of acid (eg 100cm3)
• Fill the conical flask with a known volume of alkali
• Put an indicator in the conical flask (let's say you're using phenolphthalein) 
• Using the tap, slowly drip the acid into the alkali, stirring every 10 seconds and watching carefully for the phenolphthalein to turn colorless (it's pink in alkalis) - this will mean that it's neutral. At this point, stop pouring in the acid immediately.
• Once it has turned colorless, see how much acid you've used up
• Repeat the process using the known volume of acid into the known volume of alkali without the indicator. 
• Your solution is now neutral and not contaminated with indicator :) (If you did it right, which hopefully you did)

4.5 Predict the products of reactions between dilute hydrochloric, nitric and sulfuric acids; and metals, metal oxides and metal carbonates (excluding the reactions between nitric acid and metals)

Metals

• METAL + ACID > SALT + HYDROGEN
• HOWEVER
• a metal only reacts with an acid if it is MORE reactive than hydrogen
• Metal + hydrochloric acid > metal chloride salt + hydrogen
• Metal + Sulphuric acid > metal sulphate + hydrogen
• You don't need to know
• metal + nitric acid

Metal oxides/hydroxides

• METAL OXIDE/HYDROXIDE + ACID > SALT + WATER
• the reaction will also heat up a bit
• Metal oxide/hydroxide + hydrochloric acid > metal chloride salt + water
• Metal oxide/hydroxide + nitric acid > metal nitrate salt + water
• Metal oxide/hydroxide + sulphuric acid > metal sulphate + water

Metal carbonates

• METAL (HYDROGEN) CARBONATE + ACID > SALT + WATER + CARBON DIOXIDE
• Reaction will fizz (as CO2 is being produced)
• Metal (hydrogen) carbonate + hydrochloric acid > metal chloride salt + water + carbon dioxide
• Metal (hydrogen) carbonate + nitric acid > metal nitrate salt + water + carbon dioxide
• Metal (hydrogen) carbonate + sulphuric acid > metal sulphate + water + carbon dioxide

4.4 define acids as sources of hydrogen ions, H+, and alkalis as sources of hydroxide ions, OH ̄

This basically means that if something is acidic it contains positive hydrogen ions (H+), if it is alkali it contains negative hydrogen ions (OH-)

4.3 Describe the use of universal indicator to measure the approximate pH value of a solution

    What is universal indicator?

      It is a mixture of a variety of other indicators and can be used to measure the approximate pH of a solution, however a more accurate value can be obtained using a pH probe

    

      When universal indicator is added to a solution it changes to a colour that shows the pH of the solution (using the ph scale)

o   STRONG ACIDS: red (0)

o   WEAK ACIDS: yellow (2)

o   NEUTRAL: green (7)

o   WEAK ALKALIS: blue light/dark (10-11)

o   STRONG ALKALIS: purple (14)

4.2 Understand how the pH scale, from 0–14, can be used to classify solutions as strongly acidic, weakly acidic, neutral, weakly alkaline or strongly alkaline

The ph scale is used to measure acidity and alkilinity

• Solutions with a pH less than 7 are acidic
• with 0 being a very strong (the strongest, really) acid
• and 6 (or as the number is closer to 7) being a very weak acid
• Solutions with a pH of 7 are neutral
• Solutions with a pH greater than 7 are alkaline
• where 8 (or as the number gets closer to 7) is a very weak alkali
• and 14 is a very strong (the strongest) alkali
• 
  

4.1 Describe the use of the indicators litmus, phenolphthalein and methyl orange to distinguish between acidic and alkaline solutions

Litmus (reliable)

o   ACIDS: turns red
o   NEUTRAL: purple

o   ALKALIS: blue

·      Comes in:

o   RED litmus paper

§  ACIDS: stays red
§  NEUTRAL: stays red

§  ALKALIS: turns blue

o   BLUE litmus paper

§  ACIDS: turns red
§  NEUTRAL: stays blue

§  ALKALIS: stays blue

·      
PPhenolphthalein

o   ACIDS: colourless

o   ALKALIS: pink

§  Is insoluble in water

§  Colour changes sharply around ph of 8

·      Methyl orange

o   STRONG ACIDS: Red (3)

o   WEAK ACIDS: Orange/yellow (4-14)

o   ALKALIS: Yellow

o   NEUTRAL: Yellow

§  Is yellow in both neutral and base solutions as they fall after its colour change