Question

(2pts) "Enthalpy and Entropy Changes of Dissolving Borax"

Are you completing this experiment online?

Yes

Data Collection

Record the concentration of HCl used in the experiment (M)

0.500

Table 1. Data Collection

	~60°C trial	~50°C trial	~40°C trial	~30°C trial	~20°C trial
Actual temp (°C)	60.3	50.9	39.6	29.5	18.2
Vol. borate solution (mL)	5.00	5.00	5.01	4.97	4.95
Initial buret reading (mL)	4.90	20.91	31.71	37.86	41.50
Final buret reading (mL)	20.91	31.71	37.86	41.50	43.44

(14pts) Calculations and Analysis

Use the data collected in the table above to complete the calculations in the following table.

Table view 

 List view

Table 2. Calculations

	~60°C trial	~50°C trial	~40°C trial	~30°C trial	~20°C trial
Vol. of HCl used (mL)
Moles of HCl used (mol)
Moles of borate present (mol)
[Borate] (M)
Ksp
ln(Ksp)
1/T (K−1)

(4pts) Graphing the Results

Plot your values of ln(K_sp) vs. 1/T and find the slope and y-intercept of the best fit line. Use the equation for the best fit line and the following equation

$ln\left(K\right)=-\frac{\Delta H^{\circ }}{RT}+\frac{\Delta S^{\circ }}{R}$

to calculate ΔH° and ΔS° for dissolving Borax

(1pts)

What is the slope of your best fit line in the plot?

(1pts)

What is ΔH° (kJ/mol)?

(1pts)

What is the y-intercept of your best fit line in the plot?

(1pts)

What is ΔS° (J/mol)?