distinction/merit worthy marked learner work. in depth with method, pictures and working out. full completion of the applied science course, coming out with an overall merit.
Calorimetry is the process of measuring the amount of heat released or absorbed during a chemical reaction.
Energy can be released as light, sound or electrical energy. But it is most often released as heat energy.
Measuring heat transfers is called calorimetry. It is also a crucial part of thermodynamics (study of the effects
of work, heat, and energy). In order to measure the heat of a reaction, the reaction must be isolated so that no
heat is lost to the environment. Testing for temperature change it must be carried out in a controlled
environment so there are limited affecting factors which could change results. This is a part of fair testing
which ensures several variables must be kept constant (control variable). For example, testing water, ensure
distilled pure water is being used as different chemicals can affect the boiling or point (a mixed substance, two
or more types of atoms). Also, many other concepts such as: the volume of water used, starting temperature
of the water and the intensity of the flame from the Bunson burner. More reliable results can be obtained by
repeating the experiment many times. The biggest source of systematic error in calorimetry is usually
unwanted heat loss to the surroundings. This can be reduced by insulating the sides of the calorimeter and
adding a lid to keep the environment controlled and constant (1). Calorimetry also plays a large part of
everyday life, controlling the metabolic rates in humans and consequently maintaining such functions like body
temperature (4).
Temperature, measured in degrees Celsius, is how hot an object or substance is (Temperature change =
temperature of substance after heating – temperature of substance before heating). The more heated, the
more kinetic energy this object/substance has which is a result of more frequent collisions between particles
(therefore making it hotter). Energy can be released or absorbed in many forms, but in this case, heat. When
energy is released as heat, the process is exothermic, and when heat is absorbed, the process is endothermic
(2). This is because energy is either being gained within the chemical reaction or to the surroundings. When a
substance cools to its freezing point it then has a state change called freezing/solidifying. During this state
change particles will change their arrangement, closeness and motion into a tightly, regular formed
arrangement (solid) (3). During this, particles will lose energy as forces of attraction form between them. As
the substance cools, heat energy is dissipated into the surroundings (exothermic). This loss of energy is classed
as wasteful energy as the energy that is not useful for the intended purpose and is dissipated to the
surroundings. Temperature is measured by a thermometer which typically has a scale of 1 degree Celsius each
time. During practical's I have tested both a digital thermometer and liquid alcohol thermometer to determine
which produces more accurate results.
During this report I will explore how time and temperature link to the cooling curve of substances and be able
to determine the different stages within cooling through the use of the line of best fit. A cooling curve is a line
graph that represents the change of phase of matter. The independent variable (X-axis, time) is what changes
and the dependent variable (Y-axis, temperature) is what is measured (12).
Calibration of digital thermometer and liquid alcohol thermometer:
Calibration of thermometers is important as it certifies an accurate reading when testing the temperature of
something. Accurate readings are needed as thermometers are frequently used to monitor processes in
technology and industry such as medicine, meteorology and in this case scientific study (10).
,Thermometers can either be calibrated by heating icy distilled water or regular distilled water. I calibrated
them through the icy distilled water method as it gave more range of temperature leading up to the boiling
point, this fully ensures accuracy
Risk assessment:
To ensure experiments/practicals are carried out safely and sufficiently there are safety considerations of
possible risks due to both chemicals and glassware being used in the lab, therefore for a risk assessment it is
vital to observe essential safety rules and practices (6). A qualified lab technician should be present every time
equipment is in use as they observe and control the environment to preserve safety.
Glassware Is a physical hazard as it can break. Be careful when handling and put broken
equipment in the sharps bin.
Bunson burner Presents a fire risk and burn hazard. The open flame burns at high temperatures and
may ignite surrounding materials resulting in serious damage or burns. A gas leak left
undetected or gas taps left open/on can pose an explosion risk which can cause
damage and injury (5).
Further precautions for using a Bunsen burner are:
-ensure the Bunsen burner is away from any overhead shelving or equipment
-allow the gas tap to be safely accessible without coming into contact with the flame
-remove all close materials from the work area before lighting
-flammable liquids must not be near the Bunsen burner when lit
-tie back any long hair, take off dangling jewellery, tuck in loose clothing and preferably wear goggles
-ensure gas taps are turned off after use
-check that the hose fits securely on the gas valve and the burner
-do not leave open flames unattended (qualified lab technician should also be present)
-allow the burner to cool before handling to prevent risk of injury
(5)
Equipment:
-100cm3 beaker
-distilled ice
-digital thermometer
-liquid alcohol thermometer
-Bunson burner
-heat proof mat
-tripod
, Method (same for liquid alcohol and digital thermometer):
1.set up a station with a Bunson burner and tripod, heat mat underneath to prevent damage to work surface,
after fitting the Bunson burner hose to a gas tap, half open the air hole and use a match to light it forming a
roaring flame (less oxygen supply, hotter than blue flame)
2.fill a beaker with distilled ice (pure so boiling point is not affected)
3.place on the tripod so Bunson burner is sufficiently heating it
4.put digital/liquid alcohol thermometer in ensuring the probe is not touching the sides of the beaker as they
will heat to a different temperature to the icy distilled water
5.record temperature every 1 minuet for roughly twenty minutes as that is when boiling should occur (100
degrees Celsius)
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