why do we need to use moles when we try to determine amounts of reactants and products in a reaction?

If two objects at different te,peraure are in contact with each other what happens to their temperature

Answer asap need it by wednesday morning calculate the ph of 0.02m hcl best answer will be brainliest

4.25g sample of solid ammonium nitrate dissolves in 60.0g of water in a coffee-cup calorimeter, the temperature drops from 22.0 c to 16.9 c. assume that the specific heat of the solution is the same as that of pure water. calculate delta(h) (in kj/mol nh4no3) for the solution proces.