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Table of Contents

- What apparatus is used to measure cm3?
- Which piece of apparatus is used to measure 1.5 cm3 of a solution accurately?
- Which is more accurate pipette or burette?
- What is difference between Class A and Class B glassware?
- Are most pieces of glassware designed to be heated?
- What is tolerance of volumetric glassware?
- How do you calculate tolerance?
- What is the tolerance of a 10 mL graduated cylinder?
- What is more accurate than a measuring cylinder?
- What is the precision of the 50 mL graduated cylinder?
- What is precision in statistics?
- What is precision sample?

A graduated cylinder, also known as measuring cylinder or mixing cylinder is a common piece of laboratory equipment used to measure the volume of a liquid. It has a narrow cylindrical shape. Each marked line on the graduated cylinder represents the amount of liquid that has been measured.

Beakers and Flasks The volumetric flask, designed for greater precision, is typically accurate to within 0.05%. Its uses include the preparation of solutions of known concentration.

As another important difference between burette and pipette, pipettes are more accurate in releasing liquid in smaller quantities than burettes.

Glassware designated Class A signifies a compliance with applicable construction and accuracy requirements. Class A instruments are the preferred choice for volumetric determinations. Class A flasks are ISO9000 compatible. Class B flasks are general purpose instruments with the same basic design as Class A.

Most pieces of glassware are designed to be heated.

Even Class A volumetric glassware is not absolute but rather has a tolerance from its stated nominal value. For example, a 25 mL Class A Transfer Volumetric Pipet has a capacity tolerance of ± 0.03 mL, and a 50 mL Class A Buret has a tolerance of ±0.05 mL at full capacity.

Tolerance Calculation Formulas

- c = a – b. Upper limit dimension of the closing element:
- c max = a max – b min Lower limit dimension of the closing element:
- c min = a min – b max Tolerance of the closing element (subtracting equation 3 from equation 2)
- c max – c min = a max – a min – (b min – b max )
- T c = T a + T b

10ml graduated measuring cylinder made of high quality, heavy duty Borosilicate 3.3 glass. Spout for easy pouring, and round base for extra stability. Class B tolerance, ±0.20ml as per DIN EN ISO 4788 standard.

Why use a pipette instead of a measuring cylinder? Unlike a measuring cylinder, a pipette will be more accurate with all of the sample, accounting for every drop of the substance being held within the tool.

The scale of a 50-mL buret is divided into 0.1 mL increments. Therefore, when the liquid level in a buret is read, it is read and recorded to the nearest 0.01 mL.

Precision is the degree to which future measurements or calculations yield the same or similar results — it is a measure of the spread of repeated measurement results and depends only on the distribution of random errors – it gives no indication of how close those results are to the true value.

Precision refers to how close your replicate values of the sample statistic are to each other, or more formally, how wide the sampling distribution is, which can be expressed as the standard deviation of the sampling distribution.