A-level Chemistry: 3.1.10 Acids and Bases Part 1
These flashcards summarize the key concepts of Brønsted–Lowry acid-base theory, highlighting how acids donate protons (H⁺) and bases accept them. They also explain the behavior of these substances when mixed with water, including proton transfer and relevant chemical equations.
Define Brønsted–Lowry Acids
Proton donors
Key Terms
Define Brønsted–Lowry Acids
Proton donors
When Brønsted–Lowry acids are mixed with water, they ______ ____
Release H+
State the equation for when Brønsted–Lowry acids are mixed with water
Define Brønsted–Lowry Bases
Proton acceptors
When Brønsted–Lowry bases are mixed with water, they grab ___ from ____
grab H+ from H2O
State the equation for when Brønsted–Lowry bases are mixed with water
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| Term | Definition |
|---|---|
Define Brønsted–Lowry Acids | Proton donors |
When Brønsted–Lowry acids are mixed with water, they ______ ____ | Release H+ |
State the equation for when Brønsted–Lowry acids are mixed with water | |
Define Brønsted–Lowry Bases | Proton acceptors |
When Brønsted–Lowry bases are mixed with water, they grab ___ from ____ | grab H+ from H2O |
State the equation for when Brønsted–Lowry bases are mixed with water | |
Define strong acids |
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Where does the equilibrium of strong acids and bases reacting with water lie? | To the right |
Define Weak Acids |
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Where does the equilibrium of weak acids and bases reacting with water lie? | To the left |
Acids only get rid of their protons if there’s a ____ to ____ them | Acids only get rid of their protons if there’s a base to accept them |
Write an equation for when HA (acid) reacts with B (base) | |
What happens to the position of equilibrium if you add more HA or B? | Shifts to right |
What happens to the position of equilibrium if you add more BH+ or A-? | Shifts to left |
When acid is added to water, water acts as ____ and _____ the ____ | When acid is added to water, water acts as base and accepts the proton |
Equilibrium’s far to the ___ for weak acids | left |
Equilibrium’s far to the ___ for strong acids | right |
What does water dissociate into? | Dissociates into hydroxonium ions and hydroxide ions |
Which side does the equilibrium lie on? | To the left |
State the ionic product of water (Kw) & the units | Kw = 1.0×10−141.0 \times 10^{-14} mol²·L⁻² at 25°C |
Describe how Kw is derived from the equilibrium constant |
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State what Kw is at 298K | 1.00 x 10-14 mol² dm-6 |
State what the Kw expression is at pure water | Kw = [H+]2 |
Explain why Kw = [H+]2 in pure water | In pure water, there’s always one H+ ion for each OH- ion |
What is the pH scale? | Measure of hydrogen ion concentration |
The smaller the pH, the greater… | conc. of H+ ions |
State the equation you can use to work out pH (used for strong acids directly) | |
State the equation for calculating hydrogen ion concentration | |
What is meant by strong monoprotic acids? e.g. HCL and HNO3 (nitric acid) |
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What is meant by strong diprotic acids? e.g. sulfuric acid |
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What should you use to calculate pH of a strong base? | |
Why do you have to use Ka (acid dissociation constant) to work out the [H+] for weak acids? |
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As only a tiny amount of HA dissociates | |
State Ka expression you use for weak acids in aq solution with nothing else added. Include the units. | |
State the equation for calculating pKa | pKa = -logKa |
State the equation for calculating Ka | Ka = 10-pKa |
When a ___ acids reacts with a ___ base, for every mole of OH- added, ___ mole of HA is used and ___ mole of A- is formed | When a weak acids reacts with a strong base, for every mole of OH- added, 1 mole of HA is used and 1 mole of A- is formed |
6 moles of HA with 1.3 moles of Ba(OH)2. State the moles before and after the reaction. | Before reaction:
Reaction: Ba(OH)₂ provides 2 OH⁻ per mole → 1.3 × 2 = 2.6 mol OH⁻ HA is monoprotic → 1 mol HA reacts with 1 mol OH⁻ After reaction:
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Weak Acid + Strong Base Calculate the pH of the solution formed when 30 cm3 of 0.200 mol dm-3 ethanoic acid (pKa = 4.76) is added to 100 cm3 of 0.100 mol dm-3 NaOH. | pH = 5.16 |
Weak Acid + Strong Base Calculate the pH of the solution formed when 50 cm3 of 0.500 mol dm-3 ethanoic acid (pKa = 4.76) is added to 75 cm3 of 0.200 mol dm-3 NaOH | pH = 5.05 |
When ___ of the HA molecules have reacted with OH-, ____ = ∴ = ___ or ____ = ____ | When half of the HA molecules have reacted with OH-, [HA] = [A-] ∴ Ka = [H+] or pKa = pH |
Calculate the pH of the solution formed when 100 cm3 of 0.2 mol dm-3 ethanoic acid (pKa = 4.76) is added to 40 cm3 of 0.250 mol dm-3 KOH. | pH = 5.20 |
Draw the pH curve for a strong acid/strong base. Include where the graph starts and where it levels off. | |
Draw the pH curve for a strong acid/weak base. Include where the graph starts and where it levels off. | |
Draw the pH curve for a weak acid/strong base. Include where the graph starts and where it levels off. | |
Draw the pH curve for a weak acid/weak base. Include where the graph starts and where it levels off. | |
What is the name given to the section that is vertical on the pH curve? | Equivalence point or end point |
At equivalence point or end point, a tiny amount of base/acid causes a … | sudden, big change in pH |
What happens to the pH curves when you titrate a base with an acid instead? | Shapes of the curves stay the same but they flip over |