Balancing out Fe +h2O fe3O4 +H2

Which mathematical relationship should you us to convert moles of a substance into grams

According to the diagram; a) identify the anode of the cell and write the half-reaction that occurs there b) write the overall equation for the reaction that occurs as the cell operates c) calculate the value of the standard cell potential ,e cell. d)write the shorthand notation of the cell above e)indicate the flow of the electrons on the diagram

What will most likely happen when two bromine atoms bond together?