OCR A-Level Chemistry: Chapter 20 - Acids, Bases, and pH
This flashcard set introduces the Bronsted-Lowry definitions of acids and bases, explains conjugate acid-base pairs, and illustrates proton transfer using HCl and water. It highlights the formation of the hydronium ion when water acts as a base.
What is a Bronsted-Lowry acid defined as?
A proton donor
Key Terms
What is a Bronsted-Lowry acid defined as?
A proton donor
What is a Bronsted-Lowry base defined as?
A proton acceptor
What is a conjugate acid-base pair?
Two species that can be interconverted by transfer of a proton.
In the dissociation of HCl to H+ and Cl-, identify the conjugate acid and base.
HCl releases a proton so is therefore the conjugate acid.
Cl- accepts a proton so is th...
When water is the base, what is formed?
H(3)O+
Hydronium ion
What do the terms monobasic, dibasic and tribasic refer to?
The total number of hydrogen ions in the acid that can be replaced per molecule in an acid-base reaction.
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| Term | Definition |
|---|---|
What is a Bronsted-Lowry acid defined as? | A proton donor |
What is a Bronsted-Lowry base defined as? | A proton acceptor |
What is a conjugate acid-base pair? | Two species that can be interconverted by transfer of a proton. |
In the dissociation of HCl to H+ and Cl-, identify the conjugate acid and base. | HCl releases a proton so is therefore the conjugate acid. Cl- accepts a proton so is therefore the conjugate base. |
When water is the base, what is formed? | H(3)O+ Hydronium ion |
What do the terms monobasic, dibasic and tribasic refer to? | The total number of hydrogen ions in the acid that can be replaced per molecule in an acid-base reaction. |
How can redox reactions be simplified? | Remove the spectator ions |
What is the word equation for the reaction of an acid and a metal? | acid + metal -> salt + hydrogen |
What is the word equation for the reaction of an acid and a carbonate? |
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What is the word equation for the reaction of an acid and a base? | acid + base -> salt + water |
What is the word equation for the reaction of an acid and an alkali? | acid + alkali -> salt + water |
What is the relationship between pH and concentration of H+? | Low value [H+] = high pH High value [H+] = low pH |
What is the equation for working out pH from [H+]? | pH = -log[H+] (base 10) |
How is the pH calculated for a strong acid? | Assume it fully dissociates Therefore [H+] = [HA] |
How is the new pH calculated for a strong acid on dilution? | Work out change in concentration of HA and therefore [H+] Then put back into pH = -log[H+] |
How is the pH calculated for a weak acid? | Ka = [H+][A-]/[HA] Ka[HA] = [H+][A-] [H+] = [A-] [H+]^2 = Ka[HA] [H+] = sqrt(Ka[HA]) |
What is Kw? | The ionic product of water |
What is the value of pKw? | 14.00 |
How can pH of strong bases be found when given the concentration of OH-? | pKw = pH + pOH |
How can pH of weak bases be found when given the concentration of OH-? | Similar method to weak acids, with the additional step of pKw = pH +pOH |