A 100.0 mL of 0.500 M HBr at 20.29 oC is added to 100.0 mL of 0.500 M KOH (also at 20.29 oC). After mixing, the temperature rises to 23.65 oC. Calculate the heat of this reaction. [assuming the density and specific heat of HBr and KOH is the same as water, 1.0 g/mL; 4.18 J/g oC, and the volume of the solution is additive].

Answer : The heat of this reaction will be, 2.81 kJ

Explanation :

First we have to calculate the mass of water.

Given:

Density of water = 1.0 g/mL

Volume of water = 100.0 mL + 100.0 mL = 200.0 mL

Now we have to calculate the heat of this reaction.

Formula used :

where,

q = heat = ?

m = mass of water = 200.0 g

c = specific heat of water =

= final temperature =

= initial temperature =

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

Thus, the heat of this reaction will be, 2.81 kJ

number of molecules / avogadro's number * molecule molecular = mass

explanation:

we define a gram-molecular weight as the mass of one mole of any element or compound. a mole contains avogadro's number of units (molecules) –  

6.022

x

10

23

. so, dividing the number of molecules by avogadro's number gives us the number of moles. multiplying that by the molecular weight gives us the mass. from the periodic table we find the gram-molecular weight of u to be238 and of f to be19. so,  

u

f

6

will have a gram-molecular weight of 352g.

the density(ratio between mass and volume as m/v) decreases from top to bottom in periodic table group as the size increases and nuclear charge decreases. but in periods density increases from left to right as atom size decreases and nuclear charge increases.