Answer:
-15.24 kJ/mole of LiOH
Explanation:
<em>General considerations:
</em>
-A coffee-cup calorimeter is a device that works at constant pressure. Since enthalpy (ΔH) is defined as a heat flow at constant pressure, the coffee-cup calorimeter is usually used to measure enthalpy changes in processes at constant pressure.
-The high heat capacity of calorimeter indicates its difficulty to vary its temperature.
-The calorimeter absorbs a negligible amount of heat.
<em>Information given in the statement:</em>
<em>Intial temperature = </em>23°C
<em>Final temerature = </em>34.65°C
<em>Mass of LiOH=</em> 10 g LiOH
<em>Mass of solution</em> =
<em>Specific heat capacity of the solution</em> =
Converting specific heat capacity to kJ/(g°C) =[/tex]
<em>Calculations:</em>
To determine the dissolution enthalpy of LiOH, we can use the following equations:
<em>Equation 1</em>
<em>Equation 2</em>
= enthalpy of dissolution per mole of LiOH (kJ/mole).
= heat released by dissolution (kJ).
=heat absorbed by the solution in calorimeter (kJ)
.
m=mass of solution (g).
C=specific heat capacity of the solution (kJ/g°C).
ΔT=chage of temperature of the solution in calorimeter, final temperature minus initial temperatrue (°C).
Molecular weight of LiOH=23.95 g/mole
Replacing the given data in equations 1, 2 and 3, we get:
Note: Usually exothermic reactions like LiOH dissolutions, that release heat, results in negative enthalpy.