CBI2 - Fundamentals of Chemistry II Flashcards
What are the three ways of describing concentration, including units.
Molar concentration ( mol/dm3). Mass concentration (g/dm3). Volume concentration (v/v %).
Difference between dilution ratio and dilution factors.
Dilution ratio 1:10 means 11 parts total (1 part sample, 10 parts solvent).
Dilution factor 1:10 means 10 parts total (1 part sample, 9 parts solvent).
Define serial dilution.
Where solution made is used as stock solution for following dilution.
Formulas for calculation concentration/volume with two solutions.
C1 x V1 = C2 x V2
Define Ka.
Acid dissociation constant for weak acids.
Why is water ignored in acid dissociation constant.
Very large concentration/activity therefore its effect is considered constant.
Define and discuss ionic product of water.
Kw = [H+][OH-]
Used to calculate pH of strong bases. Value of 1 x 10-14 at room temperature.
Define Bronstred Lowry acids and bases.
Acid - proton donor. Base - proton acceptor.
Is high pKa associated with strong or weak acids.
High pKa = low Ka = weak acid.
How to calculate pH of strong acid.
Use pH = -log[H+].
How to calculate pH of weak acids.
Use formula for Ka. Assume [H+] = [A-]. Rearrange for [H+] and calculate pH.
How to calculate pH of strong base.
Use Kw = [H+][OH-]. Rearrange for [H+] and calculate pH.
Define relationship between pH and pOH.
pH + pOH = 14.
Define buffer solution.
A solution that maintains its pH when small amounts of acid or base are added to it. Works best with +/- 1 of pKa.
How are buffers produced.
Weak acid and conjugate base.
Weak base and conjugate acid.
How does a weak acid and conjugate base result in a buffer solution.
Weak acid partially dissociates releasing some conjugate base. Salt of acid added provided more conjugate base until complete dissociation.
Define Henderson-Hasselbach equation.
pH = pKa +log[A-]/[HA].
When does pH = pKa.
Using HH equation, when concentration of undissociated acid is equal to conjugate base concentration. Point is known as half neutralisation point.
Define Avogadro’s constant.
Number of a species in a mole. 6.022x10*23/mol.
Define and give value of Avogadros constant.
6.022 X 10^23. Defines number of particles in a mole.
Define molarity.
Same as molar concentration. Moles divided by volume.
Difference between formula and molecular mass.
Molecular mass - mass of one molecular of a substance.
Formula weight - used when substance does not exist as one molecule e.g. ionic lattices.
Notations for avogadros constant.
Na or L
What is a stock solution.
Initial solution used to create a serial dilution.
Discuss activity vs concentration.
Concentration and activity are similarly linked. Activity has no units.
Value for ionic product of water.
Kw = 1.0 X 10^-14
Define Lewis acids and bases.
Electron pair acceptor. Electron pair donor.
What does a low Ka indicate.
Low Ka = high pKa = weak acid.
Is Ka/pKa high or low for strong acids?
High Ka, low pKa.
Discuss Henderson Hasselbach equation.
pH = pKa + log([base]/[acid]) pH = pKa at half neutralisation point.
