Titration

Question 1

The strategy: Neutralize the acid

Answer 1

• We can use base to neutralize an acid, as we know the concentration and volume of the base
• If we know the amount of base required to react completely with acid, then we can use mol ratios to to find the amount of acid
• We want to completely react the acid with the base, nothing left over

Question 1

Goal for titration

Answer 1

• We have a flask that has a known volume
• however, the concentration of this acid or base is unknown
• out goal is to figure out this conecntration

Question 2

Adding enough base

Answer 2

• As we add our base, we stop when the pH will be 7 as the acid is all gone (neutral)
• The acidity decreases when we add a base
• Only for strong acid and strong base reactions
• This is the equivalence point

Question 3

Reaching the equivalence point

Answer 3

• Can be done through pH probe, but very expensive
• Acid-Base indicators can be used to change the colour of the solution at the equivalence point

Question 4

Acid-Base Indicators

Answer 4

• They do not change colour at a specific pH value; they change colour over a range
• The ideal acid-base indicator changes colour at the steepest part of the titration graph (at the same volume)
• It does not matter which indicator you use because they are on the steepest part of the graph and the volume you added stays the same

Question 5

Three types of Acid-Base Indicators

Answer 5

• methyl red
• bromothymol blue
• phlenlophien

Question 6

Titration

Answer 6

using equvilance point and stichmetery to find the concentration of analyte

Question 7

Titrant

Answer 7

The known concentration of the solution/Standard solution

Question 8

Analyte

Answer 8

The Unknown concentration of the solution/Sample

Question 9

equivlance point

Answer 9

When moles of acid and moles of base are equal to each other, they neutralize

Question 10

Endpoint

Answer 10

The point in a titration when there’s a sudden change in color from the acid-base indicator

Question 11

Equivalence point vs. Endpoint

Answer 11

• Endpoint is an estimate of the equivalence point
• Multiple trials of titration is recommended to find that average endpoint
• You need the correct pH indicator to based on equivalence point

Question 12

Practical details

Answer 12

• The titrant in the burette does not need to be at 0
• The meniscus line must touch the line
• We subtract the initial volume to the final volume that reached the endpoint
• We know we reached the endpoint when a single drop of titrant creates a colour change and doesn’t fade

Question 13

Titrations and standard solutions

Answer 13

• To make the titrant accurate, the concentration of the titrant must be precisely known
• This is why standard solutions are used as the titrant
• Standard solutions can be hard to prepare (if a pure solid form of the compound is hard to obtain) and potentially unstable

Question 14

Titrations and NaOH

Answer 14

• NaOH can react with CO2 in the air to form carbonate compounds
• These decreases the concentration of NaOH in the solution
• The concentration of the titrant/standard solution can be confirmed using a primary standard as analyte before titration
• We tritrant the NaOH to see if it’s the same concentration, if not we need to make a new solution

Question 15

Standardizing the standard

Answer 15

• Primary standard: A compound that is highly pure and chemically stable
• It can be used to prepare an analyte with a precise concentration
• Standraize Bases: Use KHP
• standraize acids: Use Na2CO3
• Since we know the moles of the analyte (via C and V) when using primary standards, the mols of the titrant are also known (via chemical equation)
• Using this we can find the concentration of titrant