Ch. 4 Volumetric Analysis Flashcards
difference between equivalence point and endpoint
o Equivalence point: The point when the reactants are present in the ratio shown by the mole ratio in the balanced chemical equation for the reaction
Endpoint: the physical sign that indicates that the equivalence point has been reached
How to identify which indicator to use in a reaction
identify the pH of the salt made
Which indicator is used for a strong acid and strong base
bromothylmol blue (neutral)
Which indicator is used for a strong acid and weak base
methyl orange (acidic)
Which indicator is used for a weak acid and strong base
phenolphthalein (basic)
whats a primary standard
a solution of accurately known concentration that remains stable under common laboratory conditions for extended periods of time
what are examples of primary standards
Na2CO3, NaHCO3
what are 5 conditions for a primary standard
♣ Affordable ♣ Large molar mass ♣ High purity ♣ Stable ♣ Dissolve readily in solvent
what is a tritrant and analyte
- The solution in the burette= titrant
- The solution to be analysed (unknown concentration solution) = analyte
Steps for basic titration calculation
- Write balanced equation
- Moles of titrated (known) substance (c x v)
- Moles of unknown concentration substance (using mole ratio)
- Concentration of unknown (c/v)
calculation for dilution
- co.Vo =cd.Vd
what does a titration curve look like for strong acid and strong base
- pH starts high (basic region)
- Drops from 12-13 to 1-2
- Equivalence point= midpoint
what does a titration curve look like for strong base and weak acid
- pH starts at high (basic region)
- 12-13 to 4 pH
what does a titration curve look like for weak base and strong acid
- Starts high, basic region
- Remains fairly constant until close to equivalent= decrease
- Smaller than other curves
