I'm glad you guys are enjoying this extra-detailed-down to-atomic level explanation of central heating problems.
The fundamentals of water corrosion are shown in my last post.
Water (H2O) is not H2O. It is H2O <==> H+ & OH-, ie it's an 'equilibrium' of H+ and OH- ions, which move around each other. These constant exchanges of H+/OH- ions actually produce water's own electrochemical potential, measured in milli-Volts - it can be measured relative to a standard Calomel reference electrode. Also, BECAUSE OF this self ionisation of water (H2O <==>H+/OH-), anything immersed in water will be immediately surrounded by H+/OH- ions (detergents replace this barrier with their own polarised ionic agents to repel grease). You can actually calculate the number of H+ & OH- ions available depending on the weight of water - pH measurement (neutral value) will confirm the calculations.
One-way 'chemical' reactions like this:
Fe + HCl --> FeCl + H
, are shown like this:
Fe + 2HCl --> FeCl2 + H2
This is because:
HCl (hydrochloric acid) is ALWAYS HCl <==> H+ & Cl- in equilibrium,
ie just like water H2O <==> H+ & OH- in equilibrium,
but obviously Cl- is more potent than OH- in this example.
Question: If you add a TINY, TINY, drop of HCl to an iron/steel BUCKET of PURE and 'deoxygenated' WATER, then does anyone believe that the ONLY H+ ions/atoms attacking/corroding the bucket will BELONG to that tiny HCl drop?
ANSWER: NO - the tiny drop of HCl which is H+ & Cl- will SUPPORT the already occuring H+ reaction with the metallic bucket, as provided by water (H2O) which is H+ & OH-. In other words, the rate of 'existing' corrosion reaction increases.
Have fun.
The fundamentals of water corrosion are shown in my last post.
Water (H2O) is not H2O. It is H2O <==> H+ & OH-, ie it's an 'equilibrium' of H+ and OH- ions, which move around each other. These constant exchanges of H+/OH- ions actually produce water's own electrochemical potential, measured in milli-Volts - it can be measured relative to a standard Calomel reference electrode. Also, BECAUSE OF this self ionisation of water (H2O <==>H+/OH-), anything immersed in water will be immediately surrounded by H+/OH- ions (detergents replace this barrier with their own polarised ionic agents to repel grease). You can actually calculate the number of H+ & OH- ions available depending on the weight of water - pH measurement (neutral value) will confirm the calculations.
One-way 'chemical' reactions like this:
Fe + HCl --> FeCl + H
, are shown like this:
Fe + 2HCl --> FeCl2 + H2
This is because:
HCl (hydrochloric acid) is ALWAYS HCl <==> H+ & Cl- in equilibrium,
ie just like water H2O <==> H+ & OH- in equilibrium,
but obviously Cl- is more potent than OH- in this example.
Question: If you add a TINY, TINY, drop of HCl to an iron/steel BUCKET of PURE and 'deoxygenated' WATER, then does anyone believe that the ONLY H+ ions/atoms attacking/corroding the bucket will BELONG to that tiny HCl drop?
ANSWER: NO - the tiny drop of HCl which is H+ & Cl- will SUPPORT the already occuring H+ reaction with the metallic bucket, as provided by water (H2O) which is H+ & OH-. In other words, the rate of 'existing' corrosion reaction increases.
Have fun.