Crystals and cubes

We’ve been busy in the lab getting bits and bobs ready recently, which includes preparing (probably) the worlds largest reserves of hydrohalite! Hydrohalite is a crystal that is found in sea ice all over the worlds polar regions, but yet still remains very elusive. Participants of the workshops will get a chance to be one of of just a few people that have ever seen and handled this crystal! A photo of hydrohalite growing in our lab is shown below. Simply put, it’s the cold version of table salt (NaCl), the only differences is that the crystal structure of hydrohalite has 2 water molecules attached to it, therefore making it NaCl.2H2O.

In other news, we have also come up with a fun exercise that will be used to get the students to notice how sea ice and freshwater ice differ from each other. The picture below shows a selection of ice cubes that we have made. Some are made from seawater, and others from freshwater. There are some noticeable differences between these two types of ice that you may be able to make out from the photo alone. Students will be split into groups, each with a tray of ice cubes. The groups will compete against each other to sort the ice cubes into sea ice and freshwater ice by deducing the differences between the two types as quickly as possible!

Amazingly fast crystal growth

Here’s a sneak peak of the demonstration that we will be using to start off the workshop. It gives a brilliant insight into how crystals grow in an ordered fashion. What we see here is mirabilite (Na2SO4.10H2O) crystallising amazingly fast due to the amount of salt that had been dissolved into the solution beforehand. The reaction is quite stable, and only begins when a seed crystal is added to the solution which acts as a site for the crystal to begin growing on.

I can promise that the video hasn’t been sped up!

Calling all secondary schools in North Wales…

GET INVOLVED: A call for student demonstrators

Workshop outline

For the sake of the context of the rest of this site, it’s worth just giving a brief outline of what the ‘Crystals within Crystals: The story of sea ice’ workshop will consist of. Each workshop will last for 1 school lesson, and we aim to deliver 4 of these with each school visit.

1. Introduction (7 minutes):

•  Who we (the scientists) are, and why we’re here
• What the students will be doing in the workshop
• An introduction to ice and crystals

2. Practical #1: Freshwater ice vs Sea ice (10 minutes):

• Students will be handed samples of freshwater ice and sea ice, and will observe and describe the noticeable differences between the two materials

3. What is causing these differences (3 minutes)?

• The scientists will give an explanation for why sea ice and freshwater ice are so different

4. Practical #2: Crystals (20 minutes):

• There are two types of crystal that contribute to the difference between sea ice  and freshwater ice. In this part of the workshop the students will be given samples of these crystals and will watch as they transform before their eyes once taken out of a cold environment
• The transformation will be watched under microscopes (provided) and the students will be asked to describe what they see

5. How do scientists study crystals (5 minutes)?

• The scientists will explain to the students how some of the world’s most powerful X-rays are used to see what’s going on inside the ice that they have been looking at

6. Q & A (5 minutes):

• Students will be asked to brainstorm what they would like to look at using these powerful X-rays
• Time will be allocated for the students to be able to ask the scientists questions

 

And so we begin

Here we are then, about to set off on an exciting journey involving sea ice, crystals and X-rays. Over the next year and a half we will be delivering nearly 50 workshops to secondary schools in North Wales. The workshops will be centred around the theme of sea ice and crystals, and will importantly give students an insight into how scientists can use some of the most powerful X-rays in the world to examine how sea ice and crystals behave.

The project is funded by the Science and Technology Facilities Council and will be delivered by scientists from the School of Ocean Sciences at Bangor University.