Titration with HCl and NaOH

Titration Prep 18/10/04

Aim: Determine the concentration of a solution of sodium hydroxide solution using a standardised solution of hydrochloric acid.

Health and safety:

HCl/NaOH -corrosive-avoid spills, mop-up (gloves)

-safety glasses

-laboratory coat

Pippete fillers- take care when using in case they snap when putting on the pipette

Indicator -stains/poisonous

Method

Step 1. Wash out:

i.) the pipette, with a little of the sodium hydroxide solution

ii.) the burette, with a little of the hydrochloric acid solution

iii.) the conical flask, with a little distilled water.

Step 2. Fill the burette with the hydrochloric acid solution, running some of the solution through the tap, until the bottom of meniscus is just on the zero level. Ensure that there is no air bubbles trapped.

Step 3. Using the pipette filler place 25cm3 of the sodium hydroxide solution in the clean conical flask.

Step 4. Add 4 or 5 drops of methyl orange indicator to the contents of the flask. Note the colour.

Step 5. Using the tap on the burette run the acid into the solution of sodium hydroxide in the conical flask (shaking the flask as the acid drips in) until the solution changes colour. At this point note the reading on the burette and the colour of the indicator. This first titration is ‘rough’ so only an approximate volume of acid is required.

Step 6. Repeat steps 2, 3 and 4

Step 7. This time:

i.) Run the acid into the solution until the volume of HCl is to within 2 cm3 of what it was in the rough titration (step 5).

ii.) At ...