What is a primary standard?

Answer 1

A primary standard solution is generally a solution prepared and certified by an authorized and specialized institution (for example: NIST - National Institute for Standards and Technology).

Answer 2

1) Can be prepared and maintained in high state of purity. 2) Is unaltered in air during weighing (ie it is not hygroscopic). 3) Has high molecular farmula so that wieghing errors are negligable. 4) Will react with an appropriate solution stiochiometrically and practically instantanously.

Answer 3

1) Should be stable, in extremely pure form and solid at SATP.
2) Should have a high molecular formula so that weighing errors are negligible.
3) Should produce a colourless aqueous solution.

Answer 4

1. High purity- Can be prepared and maintained in high state of purity.
2. High Stability - stability in water is important because it has to be constant.
3. High equivalent weight -Should have a high molecular formula so that weighing errors are negligible.

Answer 5

Characteristics of a primary standard:
- Be prepared by an authorized institution
- If possible, to be agreed internationally
- Certify clearly a certain material property
- Be stable in time
- Be accompanied by an analysis bulletin and a quality certificate
- Based on this standard the preparation of secondary standards, working standards etc. will be possible

Answer 6

99.9% purity

Must be very stable when solid or in solution

Must be soluble in water

Should have a relatively high GFM (this reduces errors in mass -> calculations)

Answer 7

A secondary standard is prepared based on the primary standard; they have different labels and certificates.