7324941
Description
Flashcards by Francesca Wittmann, updated more than 1 year ago
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Created by Francesca Wittmann
almost 8 years ago
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| Question | Answer |
| Arrhenius Acid | Dissolves in water to form H+ ions |
| Arrhenius base | Dissolves in water to form OH- ions |
| Bronsted-Lowry acid | proton donor |
| Bronsted-Lowry base | Proton acceptor |
| Monotropic acid | can donate one proton per molecule e.g. HCl where as H2SO4 is ditropic |
| Weak Acid | Only partially dissociates into ions when dissolved in water |
| Strong Acid | Fully ionises in water (dissociates into its ions) |
| Conjugate Base | A substance which has donated a proton and could now accept a proton |
| Conjugate acid | A substance that has accepted a proton that could now donate a proton |
| Define Acid-Base conjugate pairs | A pair of molecules that can be transformed from one to another by the loss or gain of a proton |
| pH equation | -log[H+] |
| equation for [H+] in terms of pH | = 10^-pH |
| Things to assume when dealing with strong acids | The [H+] is the same as the concentration of the acid. i.e. [HCl] = [H+] in an equation |
| What is Ka and the Equation for it? | Ka= acid dissociation constant = [H+][A-]/[HA] units= mol/dm3 |
| Assumptions for calculating pH of weak acids? (2 things) | 1. Dissociation= so small that [HA] at equilibrium= [HA] of undissociated acid 2. [H+]=[A-] (formed in equal amounts) |
| Equation for Ka of a weak acid | Ka= [H+]^2/ [HA] |
| What is pKa and the equation for it? | pKa= -log[Ka] |
| Size of Ka and pKa for a strong acid | Large Ka therefore small pKa |
| Equation for the ionic product of water | Kw= [OH-][H+] |
| Ionic product for water at room temp | 1.00x10^-14 mol2/dm6 |
| equation combining pH and pOH | 14 =pH + pOH 14= -log[H+] -log[OH-] |
| Define End point | The point in a titration at which a colour change of pH change indicated that just enough reactant has been added from the barrette to react with the chemical in the flask |
| Define Equivalence point | The point in a titration when the amount of a reactant has been added to exactly react with the amount of chemical in the flask according to the stoichiometry of the chemical equation |
| Titration curve of a strong acid and strong base | sharp zig zag with equivalence point at pH=7 |
| Titration curve for strong acid and weak base | Zig Zag with slight curve at lower part. Equivalence point ph<7 |
| Titration curve of strong base and weak acid | Curved lower part where solution forms buffer. Equivalence point pH>7 |
| Titration curve of a weak acid and weak base | S shaped: pH change around the equivalence point is gradual |
| Assumptions when calculating pH of a buffer solution | Assume all [A-] comes from conjugate based formed in reaction. Assume all weak acid [HA] is undissociated |
| Methyl Orange: Colour change and pH (from acid to alkali) | from Red to Yellow at 3.2-4.4 |
| Methyl Red: Colour change and pH (from acid to alkali) | Yellow to Red at 4.2-6.3 |
| Bromothymol Blue: Colour Change and pH (from acid to alkali) | Yellow to Blue at 6.0-7.6 |
| Phenolphthalein: Colour Change and pH | Colourless to Pink at 8.2-10.0 |
| How does temperature affect the ionic product of water? | Remains neutral as [H+]=[OH] Position of eq shifts to the right therefore [H+] increases so pH decreases |
| Define Standard enthalpy change of neutralisation | the enthalpy change for the reaction when an acid neutralises an alkali under standard conditions to form one mole of water. |
| Standard enthalpy of neutralisation for a strong acid and strong base | -57.5 kJmol-1 |
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