O Calculations Flashcards
1
Q
What is the equation for enthalpy change of solution?
A
2
Q
How do you work out pH of a strong acid?
A
- Write out an ionisation expression for the acid
- Use molar ratios to deduce the [H+]
- Substitute into pH = -log[H+]
3
Q
How do you work out the pH of a weak acid?
A
- Write out the Ka expression for the weak acid
- Assume that [H+] is the same as [A-]
- Rearrange to make [H+] the subject
- substitute into pH = -log[H+]
4
Q
How do you work out pH of a strong base?
A
- Write out ionisation expression for the base
- Use molar ratios to deduce the [OH-]
- Substitute [OH-] into Kw
- Rearrange to [H+] the subject
- Substitute into pH = -log[H+]
5
Q
How do you work out pH of a buffer solution?
A
- Write out the Ka expression for the buffer
[A-] = salt [HA] = weak acid - Recalculate the concentrations of HA and A- in the new total volume of the buffer (C1 x V1 = C2 x V2)
- Rearrange to make [H+] the subject
- Calculate H+
- Substitute into pH = -log[H+]
6
Q
How do you work out enthalpy change of a reaction from experimental data?
A
7
Q
How do you calculate the minimum temperature a reaction is feasible at?
A
