F4 rusting of iron

less reactive metal 唔係會加速生透架咩?
應該係more reactive metal can protect iron from rusting,because more reactive metal give electrons

2012-10-21 18:05:26 補充：
咁會加速生透架

Leo, 真可惜, enthalpy & rate of reaction they're somehow related (not mentioned in A-Level syl.).

我稍後答.

Please do not directly relate "reactivity of metal" to "rate of rusting". The former is a thermodynamics parameter while the latter is a kinetics parameter.

A reaction is likely to occur, but it does not necessarily proceed fast.

2013-11-12 17:48:43 補充：
己式庚辛，we do not commonly relate "enthalpy" to "rate" of reaction although equations show them together for the transition state.

A negative enthalpy change from diamond to graphite does not mean that the conversion occurs very quickly.

It is because iron lose the electron easier than the less reactive metal, hence increase the rate of rusting.
請看清題目的less reactive metal有冇寫係完全cover iron,不完全cover iron就會increase the rate of rusting of iron,完全cover的話就係prevent iron from contacting air and water,hence prevent rusting.