Acid-Base: Hydrochloric acid v.s. Sodium carbonate

Explain the term primary standard

A water soluble substance that is stable and available in pure form

PSS = Pure, Soluble, Stable

Describe how a student should have prepared 500cm³ of the 0.05M primary standard solution from a known mass of pure anhydrous sodium carbonate, supplied on a clock glass

Rinse from clock glass into beaker and dissolve //

pour using funnel into 500cm³ volumetric flask and add rinsings of beaker //

add deionised water until bottom of meniscus on calibration mark / read at eye level //

stopper and invert several times

Describe how the liquid level in the burette was adjusted to the zero mark

Fill above the mark and adjust with tap / fill to below mark and add dropwise

Why was a pipette filler used to fill the pipette with 25.0cm³ of the sodium carbonate solution?

Safety / avoid solution getting into mouth / hygiene

Name a suitable indicator for this titration

Methyl orange

State the colour change observed at the end point

Orange → red