Answer the following about chemical protection of metal surfaces. For 10 points each:
[10h] Conversion coating or passivation of aluminum surfaces employs this anion in the Henkel Alodine process. The ester of this anion is the active component in the Phillips catalyst for polyethylene production.
ANSWER: chromate [or CrO4 2-; accept dichromate or Cr2O7 2−; accept chromate esters; prompt on Iridite]
[10m] The Parkerization method for steel conversion coating uses this acid, which is often added to soda drinks. This is the main acidic component in a solution for activating carbon and has three different pKas (“P-K-A’s”) since it is triprotic.
ANSWER: phosphoric acid [or H3PO4; accept monophosphoric acid or orthophosphoric acid; accept pyrophosphoric acid or H4P2O7; accept hydrogen phosphate or dihydrogen phosphate; reject “phosphate”]
[10e] Non-stainless steels can also be treated with the molten form of this element in galvanization to minimize rusting. Copper is alloyed with this element to form corrosion-resistant brass.
ANSWER: zinc [or Zn]
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