Chemical Changes
- Created by: RevisingBird
- Created on: 11-04-18 18:31
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- Chemical Changes
- Acids and Neutralisation
- metal + acid ? salt + hydrogen
- A salt is made when hydrogen ions in an acid are replaced by a metal ion
- Solid alkaline = base
- OILRIG
- Oxidation is less
- Reduction is gain
- Redox reaction: when oxidation and reduction happens in same reaction
- metal + acid ? hydrogen
- products always oxidised
- reactants always reduced
- Base - metal oxide or insoluble metal hydroxide
- An alkali produces OH- ions in water
- Alkali - base dissolved in water
- An alkali produces OH- ions in water
- acid + base ? salt + water
- acid + alkali ? salt + water
- H+ + OH- ? H20
- Neutralisation
- All acids form H+ ions when added to water
- Weak acids partially ionise in water
- Strong acids completely ionise in water
- Smaller conc. of H+ ions
- So they have a higher pH
- Dilute acid - more water particles
- Concentrated acid - more acid particles
- Electrolysis
- Positive ions move to the cathode
- They gain electrons ? reduction
- Negative ions move to the anode
- They lose electrons ? oxidation
- For metal and hydrogen ions the most reactive stays in solution
- Example: Sodium Chloride
- Ions to anode
- Ions to cathode: Na+ H+
- Untitled
- Positive ions move to the cathode
- Reactivity of metals
- Metal + water ? metal hydroxide + hydrogen
- More reactive metal displaces less reactive metal
- Carbon can also displace some more reactive metals
- Carbon used to remove oxygen from metal oxide = reduction
- e.g. iron oxide + carbon ? carbon dioxide + iron
- You can reduce certain metals using hydrogen e/g/ tungsten
- Unreactive metals e.g. gold can be found in native state
- Acids and Neutralisation
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