ACID-BASE TITRATION

Arrhenius acids

_____ are compounds that dissociate when added to water, resulting in free hydrogen ions (H+) in the water

Arrhenius bases

______ also dissociate when added to water, but these compounds yield free hydroxide (OH-) ions in the water

pH = -log[H+]

The concentrations of the hydrogen ions can be quantified using the pH scale using the formula ______

titration

A _____ is an experimental technique for determining the molarity of a substance (the analyte) in solution by reacting it with another substance (the titrant) for which you can keep track of the amount, or volume, of titrant reacted

molarity of a solution

Recall that ______ is defined as moles of solute per liter of solution, so a 1 M (“one molar”) solution has 1 mole of solute in 1 liter of solution.

acid-base titration

An _______ is essentially a controlled neutralization reaction between one aqueous solution of a known concentration (called a titrant or standard) and one aqueous solution of an unknown concentration (called an analyte)

basic solution

If the analyte is an acidic solution, the titrant must be a _____

acidic solution

If the analyte is a basic solution, the titrant must be a _____

titration

a technique used to measure the volume of a solution of known concentration that is required to react with a measured amount (mass or volume) of an unknown substance in solution

burette

an instrument used to measure volume; a graduated glass tube about 40 cm long with a stopcock on one end

volume measurement

The _____ is made by reading the fluid level in the buret before and after the titrant, the fluid in the buret, is dispensed through the stopcock

standard solution or titrant

a solution of known concentration

analyte

a substance or a mixture about which something is not known

indicator

a substance which is added to the reaction system in small amounts; it indicates that the reaction is complete (has reached the end point) by changing color.

end point

the stage in the titration at which the indicator color change is observed, indicating that the reaction is complete.

NaOH

Procedure #1 Rinse Equipment: Rinse the burette with a small amount of _____ solution to avoid contamination and dilute errors.

vineger

Procedure #1 Rinse Equipment: Rinse the pipette with the ____ sample

distilled water

Procedure #1 Rinse Equipment: Rinse the Erlenmeyer flask with _____

NaOH; funnel

Procedure #2 Fill the Burette: Close the burette tap and carefully fill it with the standard ____ solution using a _____

NaOH; 0.01 mL

Procedure #2 Fill the Burette: Remove the funnel and record the initial volume of _____ in the burette to the nearest ____ mL.

25.00 mL; vinegar

Procedure #3 Pipetting: Use the pipette to transfer a measured volume (____) of the ____ sample into the Erlenmeyer flask

2-3; phenolphthalein

Procedure #4 Add Indicator: Add _____ drops of ____ to the vinegar in the flask

colorless

Procedure #4 Add Indicator: The solution should remain _____ (since vinegar is acidic).

white tile or white paper

Procedure #4 Titration: Place the Erlenmeyer flask under the burette on a ____

NaOH; swirling the flask gently

Procedure #4 Titration: Slowly add ____ from the burette while _____

pink; slow the addition

Procedure #4 Titration: As the solution begins to turn ____ but quickly fades, ______

faint pink; 30

Procedure #4 Titration: When a _____ color remains for about____ seconds, stop the titration. This is the endpoint.

0.01

Procedure #5 Record Final Reading: Record the final burette reading to the nearest _____

final reading

Procedure #5 Record Final Reading: Subtract the initial reading from the ____ to get the volume of NaOH used

three; concordant

Procedure #6 Repeat for Accuracy: Repeat the titration at least three times until you get two or more ______ result

concordant volumes

Procedure #6 Repeat for Accuracy: Use the average of the _____ in your calculations.