Defenition of error

1. ANALYTICAL ERRORS
Prepared By:
Dr. Ram Babu Tripathi
Associate Prof
Ram Eesh Institute of Voc. & Tech
Edu.
Greater Noida, UP

2. WHAT IS ERROR?
Error is defined as: "The
difference between the
Measured value and True
value and” is also called
Absolute Error
If two persons use the same instrument
for measurement for finding the same
measurement, it is not essential that they
may get the same results. There may
arises a difference between their
measurements. This difference is referred
to as an "ERROR“.

3. Errors in any set
of measurements
can be divided
into the following
categories:
Systematic,
determinate
or constant
errors.
Random,
accidental or
indeterminate
errors

4. Types
of
Error
Determinate
error
Determinate error are
those for which
source can be
observed or detected
Indeterminate
error
The error are for which
source can not be
observed or not detected
or can be pinpointed.

5. SYSTEMATIC ERRORS
This type of error arise due to defect in the measuring device or
instruments is known as "SYSTEMATIC ERROR"
Generally it is called "ZERO ERROR". it may be positive or negative error.
Systematic error can be removed by correcting measurement device.

6. TYPES OF SYSTEMATIC ERRORS
I. PERSONAL ERRORS: These errors are not connected with the
method or procedure but the individual analyst is responsible for them.
This type of errors may arise due to the inability of the individual making
observations. Some important personal errors are
• Inability in judging color change sharply in visual titrations
• Error in reading a burette.
• Mechanical loss of material in various steps of an analysis.
• Insufficient cooling of crucible before weighing.
• Using impure reagents

7. II. OPERATIONAL ERRORS: These errors are mostly physical in nature and
occur when sound analytical technique is not followed.
III. INSTRUMENTS AND REAGENT ERRORS: following factors are responsible
for such errors:
 Balance arms of unequal lengths
 Uncalibrated or improperly calibrated weights
 Incorrectly graduated burettes
 Impure reagents
These errors can be avoided by using calibrated weights, glassware's and pure
reagents

8. IV. METHODIC ERRORS: These are the most serious types of errors
encountered in chemical analysis. Some examples involving methodic errors
are:
 Solubility of precipitate in medium and in wash liquid.
 Decomposition or volatilization of weighing forms of precipitates on
ignition of on heating.
 Hygroscopicity of the weighing forms of the precipitates.
Co-precipitation.
Post-precipitation
Occurrence of side reactions
These errors can be eliminated or reduced to a small magnitude by
employing the proper technique

9. Random or Indeterminate Errors:
These errors are accidental and analyst has no control over them likes
Vibration in balance while handling it Accidental loss of material during
analysis.