Hot water rises because its molecules are moving rapidly as they expand the water. Hot water is less dense, therefore, the same amount of water takes up the larger space. Hot water rises above the colder denser water. The resulting movement is called convection. The flowing displacement of a mass of cold fluid under large amounts of hotter fluid is the same phenomena seen with weather patterns where cold higher pressure air displaces and pushes up the hotter air. Hot air balloons also take advantage of this squeezing action.
The periodic table just got four new elements, but this isn’t as groundbreaking as recent headlines would have you believe. Join Speaking of Chemistry’s resident killjoy to find out why.
Seriously, though, this is some really cool chemistry. We want to thank C&EN’s elemental expert Jyllian Kemsley and chemist/chemical linguist Shawn Burdette of Worcester Polytechnic Institute for their help with this episode.
If you want more Speaking of Chemistry, like us on Facebook: http://www.facebook.com/SpeakingOfChem
And if you want to learn more about these elements, check out these great resources:
Seventh Row Of The Periodic Table Is Now Complete With Addition Of Four Elements | C&EN
By Jennifer Verge
Curriculum Connection: Grade 11 Environmental Science (University) – Scientific Solutions to Contemporary Environmental Challenges, Human Health and the Environment.
Grade 11 Environmental Science (Workplace) – Human Impact on the Environment; Human Health and the Environment. Could also link to: Grade 8 – Understanding Earth and Space Systems; Grade 9 Chemistry; Grade 9 Biology; Grade 10 Earth and Space or Chemistry; Grade 12 Chemistry
An important environmental issue is the effects of road salt on our local ecosystems. Toronto is Canada’s largest user of road salts to de-ice roads. Rock salt corrodes cars, kills plants and trees, damages bridges, and leads to the salination of our fresh water systems. It is listed by Environment Canada under the Canadian Environmental Protection Act as an environmentally toxic substance. Although road salts are considered to be the cheapest methods of de-icing our roads, it does not account for the more than six billion dollar annual damage cost to build infrastructure in North America due to the use of this corrosive material and its damage to the ecosystem (http://www.lostrivers.ca/points/saltdome.htm).
Alternative methods are available, but the purchasing of these products is initially more expensive, which is the major deterrent in relation to budget allocation and city resources. However, it is important to consider both the economic and environmental long-term costs of the use of road salt.
A student-centred, inquiry-based approach may be used to introduce this issue to a class of junior students. Instead of introducing the problem outright, the students should be allowed to design their own experiment in which they choose the best way to melt snow and ice. This would be a level three activity based on the four-level model of inquiry because students will be provided with the question, “What is the best way to remove ice and snow from the roads?” (Bell, Smetana & Binns, 2005), but the methods and solution will be based on the students’ own work. Students can do their research on which materials to use, and provide a list of these materials to the teacher, so he or she can obtain the materials. Students will also be required to include research on Toronto’s methods of de-icing the roads. This material would also be included in the experiment. Students would then collect the runoff water from each experiment and compare it to the original source of water, by testing for salt, other toxins, and pH levels. Students would then use this collected water to water and care for seedlings and see the effects of each product on the health of the plant. They would publish their results and, hopefully, make the connection on their own between the use of road salt and its detrimental effects on the environment. This will be relevant to the students because they have already done their research and understand that this is what is happening in their own city. As a follow-up to this experiment, students could research the cost of road salt and alternative methods, and do a cost-analysis which can be integrated into a math lesson.
In order for students to become scientifically literate, it is instrumental that they develop an understanding of the political and economic aspects that are integral to science and technology. One way of doing this is to introduce the idea of pertinent stakeholders. The pertinent stakeholders involved would be Environment Canada because, although they have
stated that road salts are detrimental to the environment, restrictions on the use of road salts and implementation of alternative methods are still voluntary. The City of Toronto and the Ontario government are also pertinent stakeholders because they are the ones who set the regulations and budgets for road clearing. Environmental groups such as Riversides, a Toronto-based watershed group which has studied road salt use in Ontario, and researchers and companies involved in the production and application of alternative methods are pertinent stakeholders, along with those involved in the fishing, farming, forestry, and outdoor recreation industries because of their investments in environmental protection.
Lobbyists for salt and transportation industries are pertinent stakeholders in this case because of the pressure they put on the government to perpetuate the use of road salt for the company’s bottom line. Students can research the different pertinent stakeholders. Depending on the age of the class, students can choose or be assigned to represent the point
of view of a stakeholding group, and hold a debate to defend the position of the group(s) they represent. This type of activity helps students to understand the complexity of these issues outside of the scope of the classroom, thereby creating a more authentic experience.
Once students have identified the pertinent stakeholders, they would use the results of their research from their experiment to write letters to the stakeholders as well as to media outlets such as newspapers and local news stations, to increase awareness of this issue. This would not only be a lesson in student activism — which can be seen as one of the founding
motivations of teaching through Science, Technology, Society, and the Environment — but could also be integrated into the Language Arts strands of writing and media literacy. Students could then start their own campaign within their school, homes, and local communities to stop the use of road salt to de-ice their neighbourhood roads and sidewalks in favour of alternative methods. Students can become teachers in their own right, educating their parents and family members on issues about which they are passionate, and at the same time learn to take an active role in their communities as scientists and educators.
This should be viewed as an issue of equity and social justice because the continued use of rock salt to clear roads is leading to the salination of our drinking water. Access to clean water is a basic right of all Canadians; however, if we continue to poison our fresh water sources then people will be required to either purchase filtered water or install expensive
water purification systems in their homes. These options would only be available for the economically-abled members of our society, which would lead to inequitable access to clean water.
1. Along Lost Streams: Salt Domes. (2007, May). In Points of Interest. Retrieved January 25, 2012, from http://www.lostrivers.ca/points/saltdome.htm
2. Bell, R.L., Smetana, L., & Binns, I. (2005). Simplifying Inquiry Instruction: Assessing the inquiry level of classroom activities. The Science Teacher, 72(7), 30-33.
Jennifer Verge was a pre-service teacher at OISE/UT when she wrote this article. She was a recipient of the 2012 Don Galbraith Pre-Service Teacher Award of Excellence with this submission.