KEEPING UP THE STANDARDS
UNIT 2 ASSIGNMENT A
PRATICAL SCIENTIFIC PROCEDURES AND TECHNIQUES
,Table of Contents
Introduction...........................................................................................................................................2
Hypothesis.............................................................................................................................................2
Risk assessment & Safety.......................................................................................................................3
PART A: Calibration of the thermometer...............................................................................................3
Information:.......................................................................................................................................3
Equipment list....................................................................................................................................3
Method..............................................................................................................................................3
Using ice:........................................................................................................................................3
Using boiling hot water:.................................................................................................................3
Result.....................................................................................................................................................3
PART B: Cooling curve of stearic acid.....................................................................................................4
Equipment list....................................................................................................................................4
Method..............................................................................................................................................4
Result.................................................................................................................................................4
Graph.............................................................................................................................................5
Conclusion.............................................................................................................................................6
Evaluation..............................................................................................................................................7
Bibliography...........................................................................................................................................8
1
, Introduction
Stearic acid comes from animal and vegetable fats and oils. It’s a waxy solid at
room temperature and it’s used as a soap, candles, and cosmetics ingredient.
This acid is a long chain of saturated fatty acid. Its chemical formula is C18H36O2.
Newton’s Law of Cooling states that the rate of change of the temperature of an
object is proportional to the difference between its own temperature and the
room temperature.
The convention of a substance from one state to another is called phase
changes. The phase changes are involved in changes in energy (the energy is
either released or absorbed). A graph of temperature against time can be plotted
and it’s called cooling curve. When the temperature of a liquid id decreasing it
means that also the kinetic energy is decreasing. When a liquid changes to solid,
the temperature remains the same. When it becomes solid the temperature is
lowering meaning that the kinetic energy is low.
There are two types of forces of attraction:
Intermolecular forces- between molecules
Intramolecular forces- within the molecule
Intermolecular forces varies among different substances. The force is weaker
than ionic and covalent bonds. The energy needed to break the intermolecular
attraction is much lower. However, they are strong enough to control physical
properties such as boiling and melting points.
Molecules that have permanent dipoles are attracted to each other (the positive
ends are attracted to the negative ends). These forces are only important when
the molecules are close to each other. The more polar the molecule, the higher is
its boiling point.
The shapes of the molecules affects the strength of London dispersion forces:
long, skinny molecules tend to have stronger dispersion forces than short, fat
ones. Another factors that can affect the force is the molecular weight (the
weigher the stronger force it has) and also the size of the atoms (large electron
clouds).
Hypothesis
To determine the accuracy of the thermometer
To investigate the colling curve of stearic acid and its rate of cooling
2
UNIT 2 ASSIGNMENT A
PRATICAL SCIENTIFIC PROCEDURES AND TECHNIQUES
,Table of Contents
Introduction...........................................................................................................................................2
Hypothesis.............................................................................................................................................2
Risk assessment & Safety.......................................................................................................................3
PART A: Calibration of the thermometer...............................................................................................3
Information:.......................................................................................................................................3
Equipment list....................................................................................................................................3
Method..............................................................................................................................................3
Using ice:........................................................................................................................................3
Using boiling hot water:.................................................................................................................3
Result.....................................................................................................................................................3
PART B: Cooling curve of stearic acid.....................................................................................................4
Equipment list....................................................................................................................................4
Method..............................................................................................................................................4
Result.................................................................................................................................................4
Graph.............................................................................................................................................5
Conclusion.............................................................................................................................................6
Evaluation..............................................................................................................................................7
Bibliography...........................................................................................................................................8
1
, Introduction
Stearic acid comes from animal and vegetable fats and oils. It’s a waxy solid at
room temperature and it’s used as a soap, candles, and cosmetics ingredient.
This acid is a long chain of saturated fatty acid. Its chemical formula is C18H36O2.
Newton’s Law of Cooling states that the rate of change of the temperature of an
object is proportional to the difference between its own temperature and the
room temperature.
The convention of a substance from one state to another is called phase
changes. The phase changes are involved in changes in energy (the energy is
either released or absorbed). A graph of temperature against time can be plotted
and it’s called cooling curve. When the temperature of a liquid id decreasing it
means that also the kinetic energy is decreasing. When a liquid changes to solid,
the temperature remains the same. When it becomes solid the temperature is
lowering meaning that the kinetic energy is low.
There are two types of forces of attraction:
Intermolecular forces- between molecules
Intramolecular forces- within the molecule
Intermolecular forces varies among different substances. The force is weaker
than ionic and covalent bonds. The energy needed to break the intermolecular
attraction is much lower. However, they are strong enough to control physical
properties such as boiling and melting points.
Molecules that have permanent dipoles are attracted to each other (the positive
ends are attracted to the negative ends). These forces are only important when
the molecules are close to each other. The more polar the molecule, the higher is
its boiling point.
The shapes of the molecules affects the strength of London dispersion forces:
long, skinny molecules tend to have stronger dispersion forces than short, fat
ones. Another factors that can affect the force is the molecular weight (the
weigher the stronger force it has) and also the size of the atoms (large electron
clouds).
Hypothesis
To determine the accuracy of the thermometer
To investigate the colling curve of stearic acid and its rate of cooling
2
