I'll give you the graphs that you need to look at:1st order: the graph you need to make is ln[A] vs t. If you get a straight line, the reaction is 1st order and the slope will equal to the rate constant K.2nd order: the graph you need to make is 1/ln[A] vs t. If this graph shows a straight line, the reaction is 2nd order and the slope will equal the rate constant K.
In stagnant water, some solutes tend to precipitate. When Sulfur precipitate and touch a metal, Sulfur is being reduced and the metal is oxidated. This depends of potential redox of each element.
