A1.50 g sample of solid nh₄no₃ was added to 35.0 ml of water in a styrofoam cup (insulated from the environment) and stirred until it dissolved. the temperature of the solution dropped from 22.7°c to 19.4°c. what is the heat of reaction for dissolving nh₄no₃, expressed in kj/mol?

Answer : The heat of the reaction is, 1.27 kJ/mole

Explanation :

First we have to calculate the heat released.

Formula used :

or,

where,

Q = heat = ?

m = mass of sample = 1.50 g

c = specific heat of water =

= initial temperature  =

= final temperature  =

Now put all the given value in the above formula, we get:

Now we have to calculate the heat of the reaction in kJ/mol.

where,

= enthalpy change = ?

Q = heat released = 0.0238 kJ

n = number of moles NH₄NO₃ =

Therefore, the heat of the reaction is, 1.27 kJ/mole

  the   balanced   equation   for   reaction of   ca metal   with   o2 to   produce   cao   is as below

2 ca+ o2→ 2 cao2

  explanation

the reaction is   balanced     since the   number of atoms   in reactant side is   equal to   number of atoms   in   product side.   for   example   they   are 2   atom of   ca in   reactant   side   and   2   atoms of ca   in   the product side.

  the   process   is a   meet the   requirement   of   redox   reaction because :     calcium   is   oxidized   from   oxidation state 0   to 2+   while   oxygen   is reduced from   oxidation   state   0   to 2-