Question

Some solutes have large heats of solution, and care should be taken in preparing solutions of these substances. The heat evolved when sodium hydroxide dissolves is 44.5 kJ/mol. What is the final temperature of the water, originally at 20.0 o C, used to prepare 500.0 cm 3 of 6.00 M NaOH solution

Answer 1

Final temperature of water is 83.8°C

Step-by-step explanation:

In 500.0mL of a 6.00M NaOH solution, there are:

0.5000L × (6.00mol NaOH/ L) = 3.00moles of NaOH

As the heat involved in dissolution is 44.5 kJ/mol, when the solution is dissolved:

44.5kJ/mol × 3.00moles = 133.5kJ = 133500J

Using coffee-cup calorimeter equation:

q = m×C×ΔT

Where q is heat, m is mass of water (500.0g), C is specific heat of water (4.186J/g°C) and ΔT is change in temperature

133500J = 500.0g×4.186J/g°C×(X-20.0°C)

63.8 = (X-20.0°C)

83.8°C = X

Final temperature of water is 83.8°C