EQUATIONS AND OTHER INFORMATION FOR CHM152L FINAL EXAM

Experiment A:

MM:    NaOH=40.00 g/mol

Heat Capacity in kJ/^oC: C_p = ((55.90 kJ/mol)n)/(change in T)

Heat of Reaction in kJ/mol = -C_p(change in T)/n

Where n = moles and T equals temperature

Experiment B:

General Reaction: E + S = ES = E + P

where E is the enzyme (papain), S is substrate (BAPNA),

P is products (p-nitroaniline), and ES is the enzyme-substrate complex.

p-nitroaniline is yellow in solution so its concentration can be directly related to the absorbance at the wavelength for maximum absorbance.

T=I/I_o A=-log₁₀(T)

Experiment C: Synthesis of the iron salt

Percent by Mass = (part/whole)*100%

%yield = (Actual Yield/Theoretical Yield)/100%

Experiment D:   MM:    NaSCN = 81.07 g/mol

Fe³⁺ + SCN^- = FeSCN²⁺

K_C = [FeSCN²⁺]/([Fe³⁺][SCN^-])

Wavelenght for Maximum absorbance for FeSCN²⁺ is 447 nm

Beer's Law:  A = €lC where A is absorbance, € is molar absorptivity, l is path length, and C is concentration

Experiment E:     AW:   Fe=55.847g/mol     K=39.098g/mol

pH = pK_a + log([A^-]/[HA])

Equivalent formula weight of the weak acid:

     = (grams of weak acid)/(moles NaOH to reach equivalence point)

Moles NaOH = (liters NaOH)(molarity NaOH)

H⁺ + OH^- = H₂O        Fe³⁺ + 3OH^- = Fe(OH)₃ (1 mol Fe³⁺ reacts with 3 mol of OH^-)

Experiment F:    MM g/mol   Na₂C₂O₄=134.0   C₂O₄^2-=88.00    KMnO₄=158.04

2MnO₄^-+5C₂O₄^-2+16H⁺ = 2Mn⁺²+10CO₂+8H₂O

Conversion factors (obtained from the balanced reaction)

     2 mole MnO₄^- reacts with 5 mole C₂O₄^-2

Percent by Mass Na₂C₂0₄ = (g Na₂C₂0₄)/g Unknown) x 100%

Additional Information:
Atomic Masses (g/mol):  Na=23.00    O=16.00   S=32.06    Mg=24.31     C=12.01 H=1.008 Ca=40.08

Equation for linear regression: y=mx+b

Median-: Middle Value Mean: Average Value Range = High-Low

Error = Absolute Value of the Experimental Value – True Value

Relative Percent Error = (Error/True Value) x 100%

Relative Percent Range = (Range/Median Value) x 100%