General Chemistry Questions & Answers

General Chemistry Questions & Answers -Weak Acids and Bases -5 equations to know relating to pKa and pKb - Direct relation of Ka and Kb to pKa and pkB - CORRECT ANSWER - pKa = -log[Ka] pKb = -log[Kb] Kw = 1 x 10^-14 = [H+][OH-] = Ka x Kb pKa + pKb = 14 Larger Ka = smaller pKa = stronger acid Larger Kb = smaller pKb = stronger base **know how to do hess's law** - CORRECT ANSWER - Lesson 11.8 in case you've forgotten 1 atm = ___ torr = ___ mmHg - CORRECT ANSWER - 1 atm = 760 torr = 760 mmHg 1 mol = ___atoms = ___ L at STP - CORRECT ANSWER - 1 mol = 6.022 x 10^23 atoms = 22.4 L 1 mol of gas = ____ L at STP STP = ___ atm and ____ K - CORRECT ANSWER - 1 mol of gas = 22.4 L at STP STP = 1 atm and 273 K 2 Thermodynamic Equations relating work, heat, pressure, volume, and energy - CORRECT ANSWER - Delta E = q + w w = -P(deltaV) 3 Ideal Gas Assumptions? When do gases behave most ideally? - CORRECT ANSWER - 1. the volume or size of each individual gas is insignificant. Most accurate at low pressures. 2. gas molecules collisions with each other are perfectly elastic (dont stick). No intermolecular forces. Most accurate at high tempartures and low IM forces. 3. the average KE of a gas depends only on the systems temperature. Gases behave most ideally under LOW pressures and HIGH temperatures. 3 Laws of Thermodynamics - CORRECT ANSWER - 1. Conservation of Energy 2. Entropy Increase - the combined charge in entropy of a system and its surrounding must be positive 3. Perfect Crystal at 0K = 0 Entropy - For a perfect crystal that's been cooled to 0 K (-273 degrees Celsius, called absolute zero), its entropy approaches zero. ESSENTIALLY LAW 3 IS SAYING THAT ENTROPY WILL ALWAYS BE SOME POSITIVE NUMBER