Enzyme kinetics, chemical equilibrium, osmotic pressure, corrosion, and molecular orbital visualization — interactive tools for chemistry and biochemistry.
— simulatorsQ: What is the Henderson-Hasselbalch equation used for?
A: pH = pKa + log([A⁻]/[HA]). It calculates the pH of a buffer solution. For example, a 1:1 mixture of acetic acid (pKa = 4.76) and sodium acetate gives pH = 4.76. Buffers work best within ±1 pH unit of pKa.
Q: How does electrochemical corrosion work?
A: Galvanic corrosion occurs when two dissimilar metals contact in an electrolyte. The more active metal (anode) oxidizes: Fe → Fe²⁺ + 2e⁻. Driving voltage = EMF difference between metals (e.g., Fe vs Cu: ~0.78 V). Protection methods include cathodic protection and sacrificial anodes.
Q: What determines reaction order and rate constant?
A: Reaction order is determined experimentally from rate = k[A]^m[B]^n. The rate constant k depends on temperature via Arrhenius: k = A×exp(-Ea/RT). A 10°C temperature rise typically doubles the rate (rule of thumb: Q10 ≈ 2).
Q: How is protein folding energy calculated?
A: Free energy of folding ΔG = ΔH - TΔS. The hydrophobic effect (burial of nonpolar residues) drives folding (ΔH < 0), while conformational entropy opposes it (ΔS < 0). Most proteins fold with ΔG ≈ -5 to -15 kcal/mol — a surprisingly small margin over thermal fluctuations.