Question

distinguish between analytical concentration and equilibrium concentration.

1- why do we say "error is inevitable"?

2- please distinguish between precision and accuracy .

Answer 1

Difference between analytical concentration and equilibrium concentration :-

Analytical concentration is the total number of moles of solute, regardless of it's chemical state in 1 L of solution. The analytical concentration describes how a solution of given concentration can be prepared. Analytical concentration is expressed as Cx.

Equilibrium concentration is the molar concentration of a particular species in a solution at Equilibrium. Equilibrium concentration is expressed as [X]. It is given by initial analytical concentration - amount reacted till the equilibrium reaches.

1) In chemistry errors are inevitable. An error is often means a mistake such as reading the scale incorrectly due to human limitations. But it's unavoidable. Errors are also occur due to the mistakes in measuring instruments, environmental influences such as humidity, temperature etc. Every instruments, how it is accurate, will have some imperfections associated with it.

We can classify errors as random errors, systematic errors and gross errors. Random errors are due to uncontrollable fluctuations in the measuring fields. Gross errors are due to carelessness of the person and also due to the instrument failures.

2) Accuracy and Precision :-

In chemistry, accuracy refers to how close the measurement value to the it's standard or known value. This is important because bad equipment, poor data processing or human error lead to inaccurate results they are not close to true, accurate value.

Precision refers to how close the series of measurements of same thing are to each other, regardless of whether the measurements are accurate or not. Precision is more important in calculations.