Titrations LAB QUIZ

What is a titration?

A quantitative laboratory technique used to determine the amount or concentration of an analyte by reacting it with a titrant.

What occurs at the equivalence point in a titration?

The amount of titrant added exactly reacts with the total amount of analyte present.

Define analyte in the context of titration.

The unknown solution whose concentration or amount is to be determined.

What is a titrant?

The standard solution of known concentration that reacts quantitatively with the analyte.

What is the endpoint in a titration?

The experimental signal used to detect the equivalence point, such as a color change of an indicator.

What is the relationship between titrant and analyte at the equivalence point?

The point in the titration where the amount of titrant added is exactly enough to completely react with the analyte according to the stoichiometry of the chemical reaction. based on moles

What are the types of titrations?

Acid-Base, Redox, Precipitation, and Complexometric Titrations.

What characterizes an acid-base titration?

The titrant and analyte neutralize each other.

What is a redox titration?

A titration that involves electron transfer between oxidizing and reducing agents.

What happens in a precipitation titration?

The reaction leads to the formation of an insoluble solid (precipitate).

What is the significance of the equivalence point?

It represents the exact stoichiometric balance between titrant and analyte, determined by the balanced equation.

How can the equivalence point be graphically identified in an acid-base titration?

It corresponds to a sharp inflection in the pH curve.

What does the endpoint indicate in a titration?

The point in a titration where the indicator changes color, signaling that the titration should be stopped. Ideally, the endpoint is very close to the equivalence point.

What is the condition for the equivalence point in an acid-base reaction?

Moles of H+ = moles of OH-.

What must occur at the equivalence point for a redox reaction?

Electrons lost = electrons gained.

What indicates that all ions have combined in a precipitation titration?

The formation of a precipitate.

What is the relationship between the equivalence point and the endpoint?

The endpoint should coincide closely with the equivalence point for accurate titration results.

What happens if excess titrant is added after the equivalence point?

Excess titrant remains unreacted as all analyte is consumed.

What is the role of stoichiometric coefficients in titration?

They determine the mole ratio between analyte and titrant in the balanced equation.

What's the first step before using the burette?

Rinse it with distilled water, then with the titrant.

After rinsing, what do you do with the burette?

Fill it with titrant and remove the funnel.

What must you check at the burette tip before starting?

That there are no air bubbles.

What reading do you take before titration begins?

The initial burette reading.

How do you measure the unknown solution (analyte)?

Pipette the specifc volume into an 125 mL Erlenmeyer flask.

What do you add to the 125 mL Erlenmeyer flask after pipetting the sample?

A few drops of indicator.

Where do you place the flask during titration?

Under the burette on a white tile/piece of paper.

How do you start adding titrant?

Add it while swirling the flask. One hand should be on the flask while the other opens and closes the stopcock.

What should you do as you get close to the endpoint?

Add titrant dropwise.

How do you know you've reached the endpoint?

The indicator shows a color change that persists.

What reading do you take after reaching the endpoint?

The final burette reading.

How do you find the volume of titrant used?

Final burette reading − initial burette reading.

How many titrations should you perform?

At least 3 trials.

What counts as concordant results?

Trials within ~0.10 mL of each other.

What do you do if one trial overshoots the endpoint?

Discard it and repeat the titration. Do not use the overshot trial in your calculation

• Once you pass the endpoint, extra titrant has been added, so the volume no longer accurately reflects the stoichiometric reaction.

• Using it would overestimate the amount of analyte.

Why can you add distilled water to the analyte flask during titration?

It does not change the moles of analyte, so it does not affect the titration results. IT HELPS MIX THE SOLUTION BETTER AND ALLOW INDICATOR TO WORK CLEARLY BECAUSE IT SLOWS THE REACTION.

Why do some titrations (like KMnO₄ titrations) require adding acid?

The reaction needs acidic conditions to occur correctly.

SNAP - ALWAYS SOLUBLE

Sodium, Nitrates, Ammonium and Potassium

STRONG ACIDS

H2SO4, HI, HBR, HNO3, HCl, HClO4

Not rinsing the equipment properly

If there’s water left in the flask where the analyte is:

• The solution is diluted, so the reaction needs more titrant to reach the endpoint.

If there’s residual acid/base in the burette:

• You might start with some titrant already in the system, so the actual titrant delivered is less than measured.

• This can make the measured volume too high or too low depending on the situation.

depends on which reactant is left

Undershooting the endpoint

• What happens: You stop adding titrant before reaching the endpoint.

• Effect on results: Volume of titrant too low → calculated concentration too low.

Overshooting the endpoint

• What happens: You add too much titrant, passing the equivalence point.

• Effect on results: Volume of titrant too high → calculated concentration too high (if titrant is used to find analyte) or analyte appears higher than it is.

• How to avoid: Add titrant slowly near the expected endpoint; swirl constantly; use a white tile to see the color change clearly.