Magnifier: the burette at the meniscus
The burette is empty. Fill it with the acid.
Start by filling the burette with the acid.
Burette
Fills to near the top. Read the initial reading at the bottom of the meniscus.
Flask
Pipette 25.0 cm³ of 0.100 mol/dm³ sodium hydroxide into a clean flask, on the white tile, and add a few drops of:
Burette tap
Place a flask under the burette to start.
Do a rough titration, then accurate titrations until two agree within 0.10 cm³. Record every burette reading to the nearest 0.05 cm³, and work out the volume of acid used each time. Choose the unit for each column heading.
| final reading/burette reading at the end | initial reading/burette reading at the start | volume used/final minus initial | |
|---|---|---|---|
| Rough | |||
| 1 | |||
| 2 | |||
| 3 |
Using only your concordant accurate titres, calculate the mean volume of acid used. Give the unit.
The flask held 25.0 cm³ of 0.100 mol/dm³ sodium hydroxide. Calculate the number of moles of sodium hydroxide in the flask.
HCl + NaOH → NaCl + H₂O. Deduce the number of moles of hydrochloric acid that reacted.
Calculate the concentration of the hydrochloric acid, to three significant figures. Give the unit.
Name the indicator you used and state the colour change at the end point.
Why is a rough titration done before the accurate ones?
State one source of error in this titration.
Suggest one way to make the titre more accurate.