Introduction to the activities This unit includes an evaluation of two de-icers: Rock salt CMA (calcium magnesium ethanoate - formerly calcium magnesium acetate) CMA is marketed as a 'greener' de-icer. There are three separate investigations: Effect of de-icer on steel (corrosion) Effect of de-icer on plant cells (osmosis) Comparison of melting caused by de-icers (lowering of melting point) Teams of students make decisions about the de-icers to be used in three sensitive locations (photographs included): In a tree-lined city square At a motorway interchange On the roads and paths surrounding a retirement home Students could be asked to suggest the different types of evidence and data that would be needed before deciding if one particular de-icer is safe and suitable for use in these locations. Many factors may be suggested by students. They might include: How well does the de-icer work? How much does the de-icer cost? Does the de-icer make the road surface slippery? How does the de-icer affect roadside plants? Will the de-icer be blown away by the wind? What happens when the de-icer drains into local streams and rivers? How will the de-icer affect the vehicles on the road? Will the de-icer damage the roads? What happens when the de-icer is stored for long periods? Is the de-icer easy to spread? Will the de-icer obscure the white lines on the road? How does the de-icer affect the soil structure at the roadside? What precautions could minimize any negative impact? The number of different perspectives that need to be considered before well informed decisions are made could be used to convince students of the importance of team work and the need for effective reporting back by individual groups to the rest of the team.
Introduction to the activities This unit includes an evaluation of two de-icers: Rock salt CMA (calcium magnesium ethanoate - formerly calcium magnesium acetate) CMA is marketed as a 'greener' de-icer. There are three separate investigations: Effect of de-icer on steel (corrosion) Effect of de-icer on plant cells (osmosis) Comparison of melting caused by de-icers (lowering of melting point) Teams of students make decisions about the de-icers to be used in three sensitive locations (photographs included): In a tree-lined city square At a motorway interchange On the roads and paths surrounding a retirement home Students could be asked to suggest the different types of evidence and data that would be needed before deciding if one particular de-icer is safe and suitable for use in these locations. Many factors may be suggested by students. They might include: How well does the de-icer work? How much does the de-icer cost? Does the de-icer make the road surface slippery? How does the de-icer affect roadside plants? Will the de-icer be blown away by the wind? What happens when the de-icer drains into local streams and rivers? How will the de-icer affect the vehicles on the road? Will the de-icer damage the roads? What happens when the de-icer is stored for long periods? Is the de-icer easy to spread? Will the de-icer obscure the white lines on the road? How does the de-icer affect the soil structure at the roadside? What precautions could minimize any negative impact? The number of different perspectives that need to be considered before well informed decisions are made could be used to convince students of the importance of team work and the need for effective reporting back by individual groups to the rest of the team.