179.1 g of water is in a Styrofoam calorimeter of negligible heat capacity. The initial T of the water is 16.1oC. After 306.9 g of an unknown compound at 94.3oC is added, the equilibrium T is 27.4oC.

What is the specific heat of the unknown compound in J/(goC)?

the specific heat of the unknown compound is

Explanation:

Generally the change in temperature of water is evaluated as

Substituting 16.1°C for and 27.4°C for

Generally the change in temperature of  unknown compound is evaluated as

Substituting 27.4°C for and 94.3°C for

Since there is an increase in temperature then heat is gained by water and this can be evaluated as

Substituting 179.1 g  for m , 4.18 J/g.C for (specific heat of water)

Since there is a decrease in temperature then heat is lost by unknown compound and this can be evaluated as

By conservation of energy law

       Heat lost  = Heat gained  

Substituting 306.9 g  for , 8459.6J for

  Therefore    

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.