UNIT 2 aim A
Practical 1: Calibration of mass balance, pipette, pH metre
What is calibration, why is it important and why do we need to calibrate?
Calibration is the process of standardising and adjusting a measuring equipment so that it
can apply with the value of the applied standard of known accuracy. In this practical, I learnt
how to calibrate a mass balance, pipette and a pH metre in order to know how to use them
and apply their uses for the practicals in this unit. The reason why I calibrated the pipette,
mass balance and pH metre is to achieve reliable results, maintain the accuracy,
standardisation and repeatability in measurements, have consistency throughout the
required practical and make sure that the measuring device is operating as expected.
Without calibration, the equipment can provide inaccurate and unreliable results, it can affect
the quality of the equipment and the accuracy of the equipment.
Risk assessment
Hazard Risk Precaution
Electrical If there is any loose wiring or screws Check if all the cables and screws are in
appliance or if the mass balance and pH metre and make sure to not have any liquids
(mass balance are faulty, you are at risk of a around electrical appliances
and pH metre) potential electrical shock
Glassware If the glass falls on the floor or on the Wearing protective personal equipment
(graduated table, it will break which can cut you such as gloves, goggles and a lab coat
pipette) and any glass that flies away could could help decrease the risk of getting
get into your skin and eyes injured
Chemicals Weak acids and weak alkalis don’t Wear protective gloves and goggles and
(weak acid, harm you a lot since they’re not very wash hands immediately if the chemicals
weak alkali,) concentrated but you could still get come in contact with your skin
some skin reactions
Thermometer Contains mercury, if it breaks it can Wear protective personal equipment such
evaporate quickly and can release as gloves/goggles/lab coats. Make sure
fumes which are poisonous when that a teacher or lab technician handles the
inhaled or if it comes in contact with broken thermometer
skin.
slip/trip/fall If there are bags and coats on the Store bags and coats in cubby holes and
floor or if chairs are not tucked under, make sure that chairs are tucked under
there is a risk of tables. Ensure there’s nothing on the floor
slipping/tripping/falling on them This that could risk slipping/tripping/falling.
could be really dangerous especially Make sure there are not too many people
if you have chemicals in your hands at an area at once
, Calculations
Mass balance
Results
Weight used (g) 10.0 5.0 1.0 0.5
Equipment reading 10.0 5.0 1.0 0.5
Difference/error 0 0 0 0
Average weight used = 4.1g
Average equipment error = 0%
Percentage error = average equipment error÷average weight used × 100
Percentage error = 0÷4.1×100
= 0%
Results from other students: 2.1% and 9.7%
Pipette
Temperature of distilled water: 16℃
Mass of distilled water: 25.02g
Volume of water = mass of water × density of water
Volume of water = 25.02 × 0.998943
= 24.99355386
Equipment error = 25 − 24.99355386
−3
= 6.44614x10
−3
Percentage error = 6.44614x10 ÷ 25 × 100
= 0.026%
Results from other students: 0.39%
Practical 1: Calibration of mass balance, pipette, pH metre
What is calibration, why is it important and why do we need to calibrate?
Calibration is the process of standardising and adjusting a measuring equipment so that it
can apply with the value of the applied standard of known accuracy. In this practical, I learnt
how to calibrate a mass balance, pipette and a pH metre in order to know how to use them
and apply their uses for the practicals in this unit. The reason why I calibrated the pipette,
mass balance and pH metre is to achieve reliable results, maintain the accuracy,
standardisation and repeatability in measurements, have consistency throughout the
required practical and make sure that the measuring device is operating as expected.
Without calibration, the equipment can provide inaccurate and unreliable results, it can affect
the quality of the equipment and the accuracy of the equipment.
Risk assessment
Hazard Risk Precaution
Electrical If there is any loose wiring or screws Check if all the cables and screws are in
appliance or if the mass balance and pH metre and make sure to not have any liquids
(mass balance are faulty, you are at risk of a around electrical appliances
and pH metre) potential electrical shock
Glassware If the glass falls on the floor or on the Wearing protective personal equipment
(graduated table, it will break which can cut you such as gloves, goggles and a lab coat
pipette) and any glass that flies away could could help decrease the risk of getting
get into your skin and eyes injured
Chemicals Weak acids and weak alkalis don’t Wear protective gloves and goggles and
(weak acid, harm you a lot since they’re not very wash hands immediately if the chemicals
weak alkali,) concentrated but you could still get come in contact with your skin
some skin reactions
Thermometer Contains mercury, if it breaks it can Wear protective personal equipment such
evaporate quickly and can release as gloves/goggles/lab coats. Make sure
fumes which are poisonous when that a teacher or lab technician handles the
inhaled or if it comes in contact with broken thermometer
skin.
slip/trip/fall If there are bags and coats on the Store bags and coats in cubby holes and
floor or if chairs are not tucked under, make sure that chairs are tucked under
there is a risk of tables. Ensure there’s nothing on the floor
slipping/tripping/falling on them This that could risk slipping/tripping/falling.
could be really dangerous especially Make sure there are not too many people
if you have chemicals in your hands at an area at once
, Calculations
Mass balance
Results
Weight used (g) 10.0 5.0 1.0 0.5
Equipment reading 10.0 5.0 1.0 0.5
Difference/error 0 0 0 0
Average weight used = 4.1g
Average equipment error = 0%
Percentage error = average equipment error÷average weight used × 100
Percentage error = 0÷4.1×100
= 0%
Results from other students: 2.1% and 9.7%
Pipette
Temperature of distilled water: 16℃
Mass of distilled water: 25.02g
Volume of water = mass of water × density of water
Volume of water = 25.02 × 0.998943
= 24.99355386
Equipment error = 25 − 24.99355386
−3
= 6.44614x10
−3
Percentage error = 6.44614x10 ÷ 25 × 100
= 0.026%
Results from other students: 0.39%
