- Releases energy
- Therefore gives out heat
- More energy is released making bonds than taken in breaking bonds
ENDOTHERMIC -
- Requires energy
- Therefore takes in heat
- More energy is taken in breaking bonds than released making bonds
4.15 recall that the breaking of bonds is endothermic and that the making of bonds is exothermic11/23/2013 EXOTHERMIC -
ENDOTHERMIC -
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Delta H = molar enthalpy change
Specific heat capacity = 4.2 J/g Mass of water = mass of water in grams Delta t = Temperature increase/decrease by the reaction
HEAT GOES DOWN = ENDOTHERMIC EXOTHERMIC -
ENDOTHERMIC -
eg. Sodium Chloride + Silver Nitrate --> Silver Chloride + Sodium Nitrate
1.7 describe techniques for the separation of mixtures, including filtration and crystallisation11/23/2013 FILTRATION -
Filtrate: the liquid which is allowed through. CRYSTALLISATION -
4.3 describe the use of universal indicator to measure the approximate pH value of a solution11/23/2013 pH 0-3: Red
pH 4-6: Yellow pH 7: Green pH 8-10: Blue pH 11-14: Purple pH 0-3: strongly acidic
pH 4-6: weakly acidic pH 7: neutral pH 8-10: weakly alkaline pH 11-14: strongly alkaline Litmus -
Phenolphthalein -
Methyl Orange -
Universal Indicator -
4.4 define acids as sources of hydrogen ions, H+, and alkalis as sources of hydroxide ions, OH¯11/23/2013 If something is acidic, then it will contain positive hydrogen ions (H+ Ions)
If something is alkaline, then it will contain negative hydrogen ions (OH- Ions) Metals above hydrogen in the reactivity series will react with acids to form a salt plus hydrogen. (eg. Magnesium Sulphate or Zinc Chloride)
METAL + ACID --> SALT + HYDROGEN Magnesium + Sulphuric Acid --> Magnesium Sulphate + Hydrogen Aluminium + Hydrochloric Acid --> Aluminium Chloride + Hydrogen Zinc + Hydrochloric Acid --> Zinc Chloride + Hydrogen Iron(III) + Hydrochloric Acid --> Iron(III) Chloride + Hydrogen ACID + ALKALI --> SALT + WATER (NEUTRALISATION REACTION)
eg. Hydrochloric Acid + Sodium Hydroxide --> Sodium Chloride + Water ACID + BASE --> SALT + WATER (NEUTRALISATION REACTION) eg. Sulphuric Acid + Copper Oxide --> Copper Sulphate + Water ACID + METAL CARBONATE --> SALT + WATER + CARBON DIOXIDE eg. Nitric Acid + Sodium Carbonate --> Sodium Nitrate + Water + Carbon Dioxide ACID + METAL --> SALT + HYDROGEN eg. Hydrochloric Acid + Magnesium --> Magnesium Chloride + Hydrogen |