A student made a model of a river in a sandbox. A pile of sand represents soil and bits of rock in the riverbed. Water
pouring from a hose represents river water as it flows
downhill.
Which two characteristics are limitations of the student's model?

What is a number added in front of a formula in order to balance the equation

How to calculate the mass of copper

Idid a lab for chemistry where we put nails in a copper (ii) chloride solution. 1. why did the reaction stop? which reactant was used up? how do you know? 2. describe what was happening to the atoms of iron and copper during the reaction. what is this type of reaction called? 3. what would happen to the ratio of copper to iron if you had placed more nails in the beaker? if you had let the reaction go for less time? 4. what is the accepted ratio of copper atoms to iron atoms in this reaction? account for differences between your experimental value and the accepted value. write the balanced equation for the reaction.