Gas laws, pressure, fluids and viscosity
Several ideas and equations in these two sections are built on the understanding of a particle model from GCSE, but the ideas have not really been defined or brought together before in this way or with the applications given (such as the storage of gas cylinders) that will be seen in a work setting. There are several ideas for practical work and contexts for this topic area in this collection and these could be taught first to develop an intuitive understanding of the concept before then using mathematical relationships to describe them.
Whilst this list provides a source of information and ideas for experimental work, it is important to note that recommendations can date very quickly. Do NOT follow suggestions which conflict with current advice from CLEAPSS, SSERC or recent safety guides. eLibrary users are responsible for ensuring that any activity, including practical work, which they carry out is consistent with current regulations related to Health and Safety and that they carry an appropriate risk assessment. Further information is provided in our Health and Safety guidance.
Episode 603: Kinetic Model of an Ideal Gas
Produced by the Institute of Physics, this learning episode allows students to relate the gas laws to the behaviour of the particles of a gas, which is important step in understanding the equations involved.
The activities include a look at:
* explaining pressure in terms of particles (which could be extended to looking at compressed gases)
* deriving an equation for the pressure of a gas
* the link between kinetic energy and pressure
Episode 602: Ideal Gases and Absolute Zero
This learning episode, from the Institute of Physics, establishes the ideal gas law and how to use it. Worked examples and questions allow students to look at the behaviour of an ideal gas and see that an ideal gas is one that obeys Boyle’s law with complete precision.
The activities include:
* a discussion of an ideal gas
* the ideal gas law (PV=NRT), moles and the Kelvin scale of temperature
Although it goes into more detail than is needed in this specification (to that needed in A level physics), there are teaching ideas and background that could be used to help teacher understanding and planning of the topic, especially around Boyle's law.
Pressure
A set of diagnostic questions and response tasks from the Best Evidence in Science Teaching (BEST) project for students aged 11-14. Although they are aimed at younger students, they would be useful as a quick introduction to pressure in fluids and include diagnostic questions and response activities on:
- Identifying factors that can increase the pressure of a fluid.
- Explaining why the pressure of a fluid is a scalar quantity that is equal in all directions.
- Explaining the effect of temperature change on the pressure of a fixed volume of fluid.
Under Pressure
This simulation can be used to explore pressure under and above water and see how pressure changes as you change fluids, gravity, container shapes, and volume.
Sample learning objectives include describing how pressure changes in air and water as a function of depth and as such could be used to supplement practical work that looks at this concept. Students might be asked to look at this with a set of questions or it could be used as a teacher demonstration with explanation.
Dangerous Rain
In this activity students consider the questions: Where does rain water go? How can we model the flow of rainwater in real life? What can be done to prevent flooding? It is an interesting real-life application of flow and so could be used for examples in class when looking an experiments or the theory behind this.
Viscosity: Stoke's law
This investigation can be used to link density (which is taught at GCSE) and viscosity together as ideas. The aim is to determine the coefficient of viscosity of a viscous liquid such as glycerol, but this could be expanded to different liquids, even ketchup, antiseptic cream or honey, as a simple investigation. This would then allow students to discuss why we would want to produce different fluids with different viscosity in real life.
Gum Fun: Investigating Plant Gums
Plant gums are often used in the food industry as thickening and stabilising agents. Gums are water soluble polysaccharides, such as starch and cellulose. In this activity, students investigate what happens to the texture when different polysaccharides are mixed. It would be a really interesting activity to bring together the structure of some biological molecules covered in the specification with fluid properties in a food science context.
Colder and colder
A cartoon-style animation that looks at the affect of reducing temperature on atoms of helium taken on a 'journey' to absolute zero. Although it is quite simple, it allows students to be able to picture what is happening to particles they cannot see and also why we might want to use low temperatures in certain contexts e.g. in a freezer.
