When a 5.00g sample of KBr is dissolved in water in a calorimeter that has a total heat capacity of 3.982 kJ-K, the temperature decreases by .210 K. Calculate the molar heat of solution of KBr.
=____kJ/mol
q in kJ = Ccal x delta T
dH/g= q/5
dH/mol = (q/5) x (molar mass KBr/mol) = ?
I have no idea!
I'm so confused
I gave you directions. Follow the directions.
Ccal = 3.982 kJ/K and delta T = 0.95.
q = Ccal x 0.95
That gives you q in kJ and
(q/5) x molar mass KBr = q in kJ/mol.
To calculate the molar heat of solution of KBr, we can use the equation:
q = -CΔT
where:
q is the amount of heat absorbed or released during the process (in this case, the dissolution of KBr),
C is the total heat capacity of the calorimeter (in this case, 3.982 kJ/K), and
ΔT is the change in temperature (in this case, -0.210 K, negative because the temperature decreases).
First, let's convert the mass of KBr from grams to moles. The molar mass of KBr is approximately 119 g/mol:
molar mass (KBr) = 39.10 g/mol (atomic mass of K) + 79.90 g/mol (atomic mass of Br)
≈ 119 g/mol
moles of KBr = mass of KBr / molar mass of KBr
= 5.00 g / 119 g/mol
≈ 0.042 moles
Now, we can calculate the amount of heat absorbed or released (q):
q = -CΔT
= -3.982 kJ/K × -0.210 K
= 0.836 kJ
Finally, we can calculate the molar heat of solution by dividing the amount of heat (q) by the number of moles of KBr:
molar heat of solution = q / moles of KBr
= 0.836 kJ / 0.042 moles
≈ 19.9 kJ/mol
Therefore, the molar heat of solution of KBr is approximately 19.9 kJ/mol.