Question

Give any two characteristics of a primary standard.


question from chemistry practicals ..class 11 (个_个)​

Answer 1

Answer:

Features of a primary standard include: High purity. Stability (low reactivity) Low hygroscopicity (to minimize weight changes due to humidity)

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Answer 2

The following are the characteristics of a primary standard in chemistry :-

• Pure ::

A primary standard is a very pure substance. Very rarely any impurity is found in them. If impurities are found, it is very easy to remove them by simple physical or chemical methods.

• Stable ::

A primary standard is a very stable substance. It has low reactivity. It can be safely placed in open environment as well as in water or air because it reacts very less and mildly. Due to this it is very stable in nature.

• Less Hygroscopicity ::

A primary standard has very low Hygroscopic property. Hygroscopicity is the property by which weight of a substance changes due to humidity. A pure substance has no or very rarely a feeble change due to humidity on them.

• Less weighing errors ::

A primary standard has very less weighing errors. This means that at whatever temperature, time, condition, etc. we measure the primary standard, the weight will be same and thus there will be very minimum weighing error.

• Non - Toxic ::

A primary standard has very less toxicity. This means that a primary standard is not radioactive and safe to use. It doesn't harm the health of the person using it.

• Good Availability ::

A primary standard is available in good amount. There's no scarcity in its availability. It is readily available for use. People can get it anytime and without much hardwork to use it.

• Cheap Availability ::

A primary substance is cheaply available in the environment. It is neither expensive nor scarcely available. A common person can use it and afford it easily according to the purpose.

• Not Deliquescent ::

A primary substance is not deliquescent in nature. This means it does not absorbs the moisture and water from the atmosphere and neither forms compound or react with water in atmosphere.

• No water of Crystallisation ::

A primary substance does not have water of hydration or it does not contain water of Crystallisation. This means it has very less moisture.

• More Molecular Weight ::

A primary substance has very high molecular weight. Since it is made up of pure substance it has no impurities, neither its weight changes so it has high molecular weight.

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★ More to know :-

• Primary Substance :: It is the standard solution or substance which has precisely known quantities of the concentrations of elements and substance which it consists of.