MARKS LOST ON PAST PAPERS Flashcards
Suggest why silicon dioxide does not conduct electricity when molten
No delocalised electrons
Test for silver nitrate and aqueous sodium nitrate
Test: Soluble chloride
Silver nitrate: white ppt
Sldium nitrate: NVC
Standard emthalpy of combustion
Standard enthalpy change when one mol of a compound is birnt completly in oxygen under tsandard condition & state
Guve a use for C6H4(CH3)(NH2)
To make dyes
Suggest why hydration of the chloride ions is an exothermic process
Water is polar
Chloride ions attracts water molecules
Observations between magnesium and water vapour
White flame
White solid
Explain why mg has a higher melting point than sodium
Mg has a higher charge than Na
So Mg has stronger metallic bonding
2 properties of macromoleculars
Insoluble
Non conductor
Expalin eny a fuel cell does not need to be recharged
Reactants supplied continuously
Suggest the main advantage of using hydrogen fuel cell rather than in an internal combustion engine
In the fuel cell, a greater proportion of the energy available from the hydrogen-oxygen reaction is converted into useful energy
Identify one major hazard associated eith the use of a hydrogen-oxygen fuel cell in a vehicle
Hydrogen is flammable
Suggest how the risk associated with the use of this drug can be minimised
Use in small amounts
Sstate why magnesium hydroxide solution could not be used for this purpose
Mg(OH)2 insoluble in water
State why silver nitrate solution is acidified when testing for iodide ions
Remove ions that react with silver nitrate
For this reaction at 1050K the equalibrium constant kp= 7.62x10^5
For this reaction at 500K the equalibrium constant kp= 3.94x10^4
Explain how this information fan be used to deduce that the forward reaction is endothermic
Kp increases ta high temperature
At higher temperature more dissociation occurs
