Sticking with Nano Presented by the MathScience Innovation Center Written by Theresa Meade

What is matter?

What is a chemical reaction? Let’s take a look at one now.

What happened? How do you know?

Today’s Lesson We will investigate the relationship between reaction rates and particle size Discover relationships between volume and surface area Make a prediction about reaction rates Conduct an experiment

Discovering Relationships What do we call the space inside a three dimensional figure? That space is called volume.

Discovering Relationships If the part inside a three dimensional figure is called volume, what is the outside called? Surface area is the outer, exposed part of a solid figure.

Time to Investigate This time we will look at a model for a solid. I will give you materials and a data sheet. Please wait for instructions!

Time to investigate What are the dimensions of your rectangular prism? 3cm

Time to Investigate How does knowing the dimensions of your prism help you determine the volume? Can you determine the volume without knowing the dimensions?

Time to Investigate How will you determine the surface area of your prism?

Time to Investigate Now you need to find out how the surface area and volume are related to each other. Use your calculator and divide the total surface area by the volume. Enter this number in the last column.

Time to Investigate Complete the rest of the table with your partner. Take apart your cubes so that you have each prism to look at. Enter all data in the appropriate column. Be sure to answer the question under the illustrations!

What did you discover? What happened to the surface area to volume ratio as the particles got smaller? Do you think this ratio will have an effect on the time it takes for a chemical reaction to occur? What is your prediction about particle size and reaction rate?

Time to Experiment! Your teacher and I will pass out supplies to each group. Two people will be timers and three people will be in charge of materials. Do not begin until we all have our materials and instructions.

Time to Experiment! While the 3 substances are in their bags, everyone in your group needs to use a magnifying lens to look at the particle sizes. On your paper, put a check by the substance you think will react fastest. Why do you think it will react fastest?

Time to Experiment! The first materials person will put substance 1 in the cup marked 1. The second materials person will put substance 2 in the cup marked 2. The third materials person will put substance 3 in the cup marked 3.

Time to Experiment! Timer 1 will time the first reaction. Materials person 1 will put 30ml (2 large spoons) of water into the empty cup. When the materials person pours the water into cup 1, timer 1 will start the stopwatch. Ready? Everyone in the group needs to record your results. What did you see?

Time to Experiment! Timer 2 will time the second reaction. Materials person 2 will put 30ml (2 large spoons) of water into the empty cup. When the materials person pours the water into cup 2, timer 2 will start the stopwatch. Ready? Everyone in the group needs to record your results. What did you see?

Time to Experiment! Timer 1 will time the last reaction. Materials person 3 will put 30ml (2 large spoons) of water into the empty cup. When the materials person pours the water into cup 3, timer 1 will start the stopwatch. Ready? What did you see?

Time to Experiment! What did you find out? Which experiment went faster? Why? How does this relate to what you found out when you investigated surface area and volume?

Time to Experiment! Pour the contents of cups 1 and 2 onto your tray. What do you notice about the particles? Was your prediction correct? How did particle size affect the reaction rate?

Time to Experiment! Let’s clean up while we wait for the third experiment to finish…

Particle Size in our World

Why Do We Care? If we can understand nanotechnology, we can create gecko-like hairs. They could enable wall climbing robots to work. They could be used in surgery instead of stitches.

Why?

From Water Bugs to… In August of 2007, scientists at the University of St. Andrews announced work with nanomachines that prevents tiny particles from sticking together. The result? Levitation!

Nanoscale… …changes everything! Forces that are important on the macroscale (like gravity) get over-ridden by forces like stickiness.

What will the future of nanotechnology be? What can you imagine?

Take one last look at your cup. What do you notice? What does this tell you about surface area and reaction rate?