If a piece of aluminum with a mass of 3.99 g and a temperature of 100.0 °C is dropped
in 10.0 cm3 of water at 21.0 °C, what will be the final temperature of the system?
(Hint: Remember the density of water is 1.00 g / mL)

The final temperature of the system is 27.3°C.

Explanation:

Heat lost by aluminum = 3.99 × 0.91 × (100-T)

                                     = 3.631 (100-T)

Heat gained by water = 10 × 4.184 × (T-21)

                                    = 41.84 (T-21)

As,

                                Heat gained = Heat loss

                          or, 3.631(100-T) = 41.84(T-21)

                          or,363.1 -  3.631 T = 41.84 T - 878.64)

                          or, (41.84+ 3.631) T = 878.64 +363.1

                          or  T=

                         or, T = 27.3°C

Hence the final temperature is 27.3°C.

a. energy is absorbed in the reaction.

if in a given reaction the energy of products is greater than the energy of reactants it means that reaction is endothermic and during the reaction, the energy is absorbed by reactants. in an endothermic reaction, the products have more stored chemical energy than the reactants. and in this reaction the reactants are more stable than products before the compounds with less energy are always more stable.