Unit 2- Practical Scientific Procedures and Techniques
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Ajmal Shekeb NOORMAL
Unit 2: Practical Scientific Procedures and
Techniques
B: Undertake calorimetry to study cooling curves
By: Ajmal Shekeb NOORMAL
Scenario
I've just started working as a technical assistant at a big chemical plant. I must demonstrate
skills in a variety of practical procedures and techniques as part of my induction period and to
advance in my position. It's part of my job to make sure that all of the equipment is calibrated
and that all of the chemicals and equipment are safe.
I need to show that I can use a calorimeter and related equipment to collect data in order to
calculate, analyze, and assess the rate at which substances cool. In a paper, I'll need to provide
proof of my functional skills research and assessment.
Assignment 2B Cooling Curve
,2
Ajmal Shekeb NOORMAL
Aim of this assignment
The aim of this assignment is to calculate the rate of cooling of stearic acid and paraffin wax and
to graph the findings using our cooling curve experiment results chart, but first we must
understand the equipment we will be using and how to calibrate it. Another experiment would
be used to determine the sensitivity of our thermometer.
As both substances, stearic acid and paraffin wax is in solid form, we should heat it using boiling
water until they become liquid. The temperature will need to be recorded every 30 seconds
until the stearic acid or paraffin wax has reached a stable temperature which remains the same
for at least 4 continuous recordings.
First of all, we need to make sure that the thermometers are accurate and we need to calibrate
them. Calibration of a scientific instrument helps to maintain accuracy of that instrument.
Thermometers: A thermometer is a device that measures temperature or a temperature
gradient (the degree of hotness or coldness of an object).[1]
The terms "heat" and "temperature" are thermodynamically related and have distinct meanings.
The transfer of thermal energy from a hotter to a cooler system when they are in contact is known
as heat transfer. Temperature is used to determine the total kinetic energy of atoms or molecules
in a system. [14]
In general, there are two types of thermometers; electronic thermometers and liquid filled
thermometers:
Types of Thermometer
Assignment 2B Cooling Curve
, 3
Ajmal Shekeb NOORMAL
Thermometer Type Principle of Operation Main Operations
Liquid-Filled: which has Alcohol in glass: a specified It is marked with degree Celsius and
liquid in it Liquid-filled amount of alcohol. Consisting of Fahrenheit, and containing alcohol which
thermometers provide a glass, capillary tube.[3] rises or falls as it expands or contracts
direct reading of the with changes in temperature.[3]
temperature. Liquid-filled Mercury in glass: consists of a bulk The volume of mercury in the tube is
thermometers are most containing Mercury attached to a much less than the volume in the bulb.
commonly used in glass tube too off narrow The volume of mercury changes slightly
technology and in the diameter. Was invented by with temperature; the small change in
laboratory for measuring physicist Daniel Gabriel Fahrenheit volume drives the narrow mercury
temperatures from –200° to in Amsterdam (1714).[4] column a relatively long way up the
750°C.[2] It has two types: tube.[4]
Electronic: are clinical Thermistor: a semi-conductor Type of resistor whose resistance is
thermometer that uses a component. [6] strongly dependent on temperature,
sensor based on thermistors, more than standard resistors. The word
solid-state electronic devices thermistor is a combination of thermal
whose electrical and resistor.[6]
characteristics change with Resistance: Also called resistant Many RTD elements consists of a length
temperature. The reading is temperature detectors (RTDs) are of fine wire wrapped around the ceramic
recorded within seconds, sensors used to measure or glass core, but other constructions are
some having a red light or temperature, it consists of fine also used. The main principle of
other device to indicate wire wrapped around the ceramic operation of an RTD is that when the
when maximum temperature or glass core but other temperature of an object increases or
is reached. these constructions are also used.[7] decreases, the resistance also increases
thermometers work digitally or decreases proportionally.[7]
and are easy to use;[5] it has Thermocouple: an electrical A thermocouple produces a temperature-
5 types. device consisting of two dissimilar dependent voltage as a result of the
electrical conductors forming an thermoelectric effect, and this voltage
electrical junction.[8] can be interpreted to measure
temperature. Thermocouples are a
widely used type of temperature
sensor.[8]
Rotary: makes use of a bimetallic The strip bends as one metal expands
strip that consists of two strips of more than the other under temperature
different metal joined together change. As temperature increases, the
surface to surface.[9] coiled bimetallic strip bends more to
rotate a pointer around on a scale.[9]
Infrared: They are sometimes An infrared thermometer is a
called laser thermometers as a thermometer which infers temperature
laser is used to help aim the from a portion of the thermal radiation
thermometer, or non-contact sometimes called black-body radiation
thermometers or temperature emitted by the object being measured.
guns, to describe the device's They can detect various wavelengths of
ability to measure temperature infrared, by knowing the amount of
from a distance. Infrared infrared energy emitted by the object
thermometers are a subset of and its emissivity, the object's
devices known as "thermal temperature can often be determined
radiation thermometers”.[10] within a certain range of its actual
temperature.[10]
Assignment 2B Cooling Curve
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