# Dissolution of Urea

Could you please show me in detail how to do this?

We were asked to repeat the procedure 3 times using different amounts of urea. Additionally, we were asked the minimum and maximum temperatures.

My answers are:

Adding 2 grams of urea and 50 mL of water:

Initial temperature = 21.00 degrees C

minimum temperature = 18.99 degrees C

Maximum temperature = 19.07 degrees C

Adding 3 grams of urea and 50 mL water:

Initial temperature = 21.00 degrees C

Minimum temperature = 18.00 degrees C

maximum temperature = 18.09 degrees C

Adding 4 grams of urea and 50 mL of water:

initial temperature = 21.00 degrees C

minimum temperature = 17.02 degrees C

maximum temperature = 17.16 degrees C

1. Calculate the heat of dissolution (q) of urea using the following formula.

q = -s m ?

where s is the heat capacity (assume the heat capacity is equivalent to the heat capacity of water: 4.184 J g-1 ºC-1, m is the mass of the solution, and ?T is the change in temperature.

2. Calculate the molar enthalpy change, equivalent to the heat of dissolution over n, where n is the number of moles of urea.

?H = q/

Here we were also asked to repeat procedure three times using different amounts of urea, However, we had to slowly add the water until the urea dissolved and record the volume of water added and the final temperature.

My answers were:

Adding 3 grams of urea

initial temperature = 21.00 degrees C

volume of water added = 2.80 mL

temperature after urea just dissolved (final temp) = 20.73 degrees C

Adding 4 grams of urea

initial temperature = 21 degrees C

volume of water added = 3.80 mL

final temperature = 20.44 degrees C

Adding 5 grams of urea

initial temperature = 21 degrees C

volume of water added = 4.70

final temperature = 20.82 degrees C

1. Calculate the equilibrium constant Keq by dividing number of moles of urea in the system by total volume of water added to the beaker in L.

2.

Calculation of ?G and ?S:

1. Calculate the free energy change of the dissolution reaction using the following formula:

?G = -RT lnKub

where R is the gas constant (8.31451 J K-1 mol-1) and T is the temperature in Kelvin.

2. Using the values of ??, ?G, and the temperature of the saturated solution, calculate ?S using the equation for Gibb?s Free Energy.

© BrainMass Inc. brainmass.com August 18, 2018, 1:50 pm ad1c9bdddf#### Solution Preview

We were asked to repeat the procedure 3 times using different amounts of urea. Additionally, we were asked the minimum and maximum temperatures.

My answers are:

Adding 2 grams of urea and 50 mL of water:

Initial temperature = 21.00 degrees C

minimum temperature = 18.99 degrees C

Maximum temperature = 19.07 degrees C

Adding 3 grams of urea and 50 mL water:

Initial temperature = 21.00 degrees C

Minimum temperature = 18.00 degrees C

maximum temperature = 18.09 degrees C

Adding 4 grams of urea and 50 mL of water:

initial temperature = 21.00 degrees C

minimum temperature = 17.02 degrees C

maximum temperature = 17.16 degrees C

1. Calculate the heat of dissolution (q) of urea using the following formula.

q = -s m ?

where s is the heat capacity (assume the heat capacity is equivalent to the heat capacity of water: 4.184 J g-1 ºC-1, m is the mass of ...

#### Solution Summary

The dissolution of urea is examined in the solution.