Important
Kp – Kc Relation
\[ K_p = K_c(RT)^{\Delta n} \]
Δn = moles of gaseous products − moles of gaseous reactants
Van't Hoff Equation
\[ \log\frac{K_2}{K_1} = \frac{\Delta H}{2.303R}\left(\frac{1}{T_1} - \frac{1}{T_2}\right) \]
Key
Reaction Quotient
\[ Q < K \Rightarrow \text{forward};\quad Q > K \Rightarrow \text{backward} \]
Important
pH Definition
\[ \text{pH} = -\log[\text{H}^+] \]
pH + pOH = pKw
\[ \text{pH} + \text{pOH} = 14\quad (at\ 25°C) \]
Kw = [H⁺][OH⁻] = 10⁻¹⁴ at 25°C
Ostwald Dilution Law
\[ \alpha = \sqrt{\frac{K_a}{C}} \]
α = degree of dissociation; C = concentration
pH of Weak Acid
\[ \text{pH} = \frac{1}{2}(pK_a - \log C) \]
pH of Weak Base
\[ \text{pOH} = \frac{1}{2}(pK_b - \log C) \]
Important
Henderson–Hasselbalch (Acid Buffer)
\[ \text{pH} = pK_a + \log\frac{[\text{Salt}]}{[\text{Acid}]} \]
Henderson–Hasselbalch (Base Buffer)
\[ \text{pOH} = pK_b + \log\frac{[\text{Salt}]}{[\text{Base}]} \]
Salt Hydrolysis – Weak Acid + Strong Base
\[ \text{pH} = 7 + \frac{1}{2}(pK_a + \log C) \]
Salt Hydrolysis – Strong Acid + Weak Base
\[ \text{pH} = 7 - \frac{1}{2}(pK_b + \log C) \]
Key
Solubility Product
\[ K_{sp} = [\text{M}^{x+}]^y[\text{X}^{y-}]^x \]
For M_yX_x → yM^x+ + xX^y−
Ksp in Terms of Solubility S
\[ K_{sp} = x^x \cdot y^y \cdot S^{x+y} \]
Degree of Hydrolysis
\[ h = \sqrt{\frac{K_w}{K_a \cdot C}} \]