Flashcards
Equilibria AS
Cards in this deck (36)
- 1Reversible reactionA reaction in which products can be changed back to reactants by reversing conditions.
- 2Equilibrium reactionA reaction that does not go to completion and in which reactants and products are present in fixed concentration ratios.
- 3Dynamic equilibriumReactants being converted to products at the same rate as products are being converted back to reactants.
- 4Closed systemA system in which matter is not lost or gained.
- 5Characteristics of dynamic equilibrium1. Rate of forward reaction = rate of backward reaction.
2. Concentrations of reactants and products remain constant.
3. It occurs in a closed system. - 6Position of equilibriumRefers to the relative amounts of products and reactants present in a reaction mixture.
- 7Le Chatelier's PrincipleIf one or more factors that affect dynamic equilibrium is changed, the position of equilibrium moves to minimise this change.
- 8Effect of concentration on the position of equilibriumIf the concentration of the reactants increases:
The position of equilibrium shifts to the right to produce more product until equilibrium is reached again.
If the concentration of the products increases, the opposite will happen. - 9Effect of pressure of position of equilibriumAn increase in pressure shifts the position of equilibrium to the side with fewer moles of gas to cause gas molecules to move further apart, increasing volume and decreasing pressure.
- 10Effect of temperature on position of equilibriumIncrease in temperature shifts position of equilibrium to the endothermic reaction so that the energy is absorbed.
- 11Effect of catalysts on the position of equilibriumCatalysts have no effect on the position of equilibrium as they increase the rate of both the forward and backward reaction equally.
- 12Equilibrium constant, Kc or KpA constant calculated from the equilibrium expression for a reaction.
Note: Kp considers only gases and Kc excludes solids. - 13Kc
- 14Factors affecting KcOnly temperature affects the value of Kc.
For an exothermic reaction:
An increase in temperature decreases Kc.
For an endothermic reaction:
An increase in temperature increases Kc. - 15Mole fraction
- 16Partial pressureThe pressure exerted by a particular gas A in a mixture of gas A, B and C.
Partial pressure = mole fraction x total pressure - 17Kp
- 18Factors affecting KpSame as for Kc.
- 19Haber process
- 20Conditions for high yield1. Low temperature because the forward reaction is exothermic.
2. High pressure because there are fewer moles of gas on the right. - 21Contact process
- 22Conditions for high yield1. High pressure (but is not actually used due to expense)
2. Low temperature because the forward reaction is exothermic. - 23NeutralisationThe reaction of an acid and an alkali to form salt and water.
- 24AcidA proton (H+ ion) donor
- 25BaseA proton (H+ ion) acceptor
Note: An alkali is a soluble base. - 26SaltA substance is formed when an acid reacts with a salt, an alkali, a metal oxide or a carbonate.
- 27Bronsted-Lowry theory of acids and basesA Bronsted-Lowry acid is a proton donor.
A Bronsted-Lowry base is a proton acceptor. - 28Strong and weak acidsA strong acid is one that is fully dissociated in solution.
A weak acid is one that is partially dissociated in solution (usually an incomplete/equilibrium reaction). - 29Strong and weak basesA strong base is one that is fully dissociated in solution.
A weak base is one that is partially dissociated in solution. - 30Distinguishing strong and weak acids1. pH values - the lower the pH, the stronger the acid due to the higher concentration of H+ ions.
2. Electrical conductivity - the greater the conductivity, the stronger the acid due to a higher concentration of H+ ions.
3. Reaction with (reactive) metals - the more vigorously bubbles are produced, the stronger the acid. - 31Indicators
- 32Titration curve: Strong base + strong acid
- 33Titration curve: Strong base + weak acidg
- 34Titration curve: Weak base + strong acidh
- 35Titration curve: Weak base + weak acidi
- 36Indicator choiceThe best indicator is the one where the end point of the reaction lies between the pH range of the indicator.
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- Chemistry Flashcards on Equilibria AS, created by Fatima Conteh on 07/02/2023.
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- Fatima Conteh
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