I've literally been trying to understand this for hours:
MgCI2 does not decompose when heated. A student inadvertently uses hydrochloric acid, HCI, instead of nitric acid in this experiment, thus forming MgCI2 rather than MgO as a product. What numerical effect will this have on the calculated atomic weight of Mg? Account for your answer.
It has something to do with Dalton's Law of Multiple Proportions, but I can't figure out what.