Question

O puntu (u pus). There LUYUCJIUNI NU Most of them are multiple choice. There are two numerical response questions and two file uploa questions, where you must submit a pdf of your work. You will have 50 minutes to complete the exam, you may not go back to a question once you answer it you can only move forward. Good luck. Question 17 6 pts When 6.30 g sample of solid potassium hydroxide is dissolved in 101.00 g of water (at 21.2 degrees Celsius) the temperature of the resulting solution is 38.8 degrees Celsius. What is the DH for this dissolution reaction? Assume the specific heat of the solution is the same as water. Only include the numerical value not units or labels. Next No new data to save. Last checked at 11:27am Submit Quiz

Answer 1

ANSWER:

Mass of KOH = 6.30 g

volume of water = 101.0 g

change in temperature, $\Delta$ T = (38.8 - 21.2) oC = 17.6 oC

Cp = 4.184 J/g oC

Now,

Mass of total solution, m = 101.0 g + 6.30 g = 107.30 g

So, amount of heat released, q = m x Cp x $\Delta$ T

= 107.30 g x 4.184 J/g oC x 17.6 oC

= 7901.4 J = 7.9014 kJ

Now,

Number of moles of KOH = (mass)/(molar mass)

= (6.30)/(56.11) moles

= 1.123 x 10-1 moles

So, dissolution enthalpy of KOH = - q/n (negative because heat is released)

= - {(7.9014 kJ)/( 1.123 x 10-1 moles)

= - 70.36 kJ/mol

Hence, the DH for this dissolution reaction is 70.36 (without unit and level).