Educational Innovations Blog

The Law of Dulong and Petit

September 3, 2011

by: Dr. Jean Oostens

Atoms were proposed in antiquity without any experimental evidence by Democritus, a Philosopher. This must have been a problem for Newton and Leibnitz who posited that there was always a mean of considering smaller and smaller intervals of space to calculate the “instantaneous velocity”.

The introduction of the precision balance in chemistry by Lavoisier paved the way for Dalton to formulate his laws on the “definite and multiple proportions” governing chemical reactions. This supported the atomic theory, without giving it general acceptance.

Specific heat was defined as the quantity of heat needed to increase one gram of a substance by one degree. There was no definite pattern when specific heats of various substances were compared. Until two French scientists in 1819 calculated specific heat by atomic mass, forming the Law of Dulong and Petit. There appeared a number of cases where the results were quite similar: about 6 calorie per mole. This was equivalent to stating that any atom is as good as any other to store heat! This was a small step towards acceptance of the existence of atoms. An explanation for this, and the reason for the exceptions, had to wait the early 20th century explanation by Albert Einstein. By that time, atoms had gained wide acceptance from the work of Rutherford, and soon by Bohr.

Lesson on the Law of Dulong and Petit:

You are given several chunks of metal, each containing 0.6 * 10²⁴ atoms (i.e. one mole) of one element. How will each of those samples, when dropped in a standard quantity of hot water (typically 200 mL and 70 C) affect the temperature?

Step 1. Use a good balance (at least 0.1 gm resolution) to determine which element you are dealing with. If possible confirm your identification with an additional cue. Read the rest of this entry »

1 Comment | Chemistry, College level, experiments, High School level, Physics | Tagged: Chemistry, Dulong and Petit Law, metals, mole, specific heat | Permalink
Posted by Tami O'Connor

Soil Porosity, Permeability and Retention Experiments

August 8, 2011

by: Cynthia House

Demonstration Materials:

125 ml graduated cylinder or similar item
~100 ml of pea gravel or small marbles
kitchen sponge
tap water

Experiment Materials:

preforms and racks (three preforms/student or group)
fine gravel such as aquarium gravel (~ 30 ml/student or group)
coarse sand* (~ 30 ml/student or group)
fine sand* (~ 30 ml/student or group)
small plastic cups ~ 100 ml capacity
squares of tulle (“bridal illusion”) and organza, ~ 10 cm x 10 cm
rubber bands
electronic balance (capacity at least 100 gm)
one pound margarine tub or similarly sized plastic cup per balance**
stopwatch or count-up timer (MyChron Student Timer)
125 ml graduated cylinder or similar item
calculators
tap water

* Home centers sell sand for sand boxes, landscaping, paving, mortar etc. Beaches are another source, although you may encounter undesirable contamination. Sifting non-homogeneous sand with a fine kitchen strainer may yield two usable grades of sand.

** secondary containment to prevent accidental spillage of water onto the balance

Background Soil Vocabulary:

Porosity is the measure of how much groundwater a soil can hold, permeability is the measure of how quickly water passes through a soil, while retention is the measure of how much water stays behind. Even elementary students can relate these concepts to their everyday lives. They observe that some areas in their yards or school grounds form puddles while others drain quickly after a rainstorm. They may wonder why one neighbor’s garden and yard remains lush and green although a sprinkler is rarely used. Children in communities dependent upon well water can understand the importance of replenishing the water table. In most rural and many suburban areas, homes use septic tanks and drain fields to process household wastewater. The “water cycle” is a topic in elementary science curricula. There are many excellent age-appropriate online sources for information on these topics including the United States Geological Survey (USGS) and the GLOBE program. Read the rest of this entry »

2 Comments | Earth Science, Elementary level, experiments, Middle School level | Tagged: average, Educational Innovations, graphing, lab processes, mean, mode, soil permeability, soil porosity, soil retention, statistical analysis | Permalink
Posted by Tami O'Connor

How to Make a Rocket (Scientist)

July 1, 2011

by: Tami O’Connor

A few months ago I had occasion to conduct two hands-on workshops for elementary and middle school teachers at the NSTA National Convention in San Francisco on behalf of Educational Innovations. One presentation focused on film canister rockets. This is a tried-and-true way to teach Newtown’s First and Third Laws of Motion and also brings to light concepts such as the four forces of flight; thrust, drag, weight, and lift. It also reinforces instruction on 3-D shapes and 2-D plane figures such as circles, cones, cylinders, rectangles, and triangles.

I presented the lesson to the teachers in much the same way I would to my students. The first thing we did was to brainstorm the features all rockets have. After a bit of discussion it was agreed that they all have a nose cone, a cylindrical body, fins, and an engine. I then handed out a paper template imprinted with the pattern of a nose cone and fins, a regular 8½ x 11 sheet of white paper, a piece of goldenrod paper, and a white translucent film canister. Also required are scissors, tape, ¼ piece of an Alka Seltzer tablet, and paper towels.

The only canister that works with this rocket is the type that has the lid that fits snugly inside the canister. The canisters that have a lid that wraps around the outside rim, however, will not allow enough pressure to build up inside the chamber.

How to Make a Rocket

The first step in building a film canister rocket is to construct the body of the rocket. The easiest way is to curl the white 8 ½ x 11 paper into a cylindrical shape using the film canister (without the top) as a guide. The paper can be rolled around the film canister and then taped along the edges. The easiest way to recover the film canister is to blow into one end of the rolled cylinder, forcing the canister out the other end. Read the rest of this entry »

3 Comments | Chemistry, Elementary level, energy, experiments, High School level, Middle School level, Physics | Tagged: Alka Seltzer rockets, energy, film canister activities, momentum, parent friendly, PBL, phenomenon based learning, phenomenon-based science, rockets, science, STEM | Permalink
Posted by Tami O'Connor

Newton’s Apple

May 28, 2011

by: Matthew Morris

Newton was a revolutionary thinker of his time. He is responsible for the three laws of motion that we still use today;

1. Objects that are not in motion remain stationary unless acted upon by another force.

2. There is a direct relationship between the force acted upon the object and the mass of that object times the acceleration the object feels (F=ma).

3. For every action there is an equal and opposite reaction.

Nobody before Newton could explain why objects acted the way they did, but with these three laws he quantified movement in terms everyone could understand.

But there was a problem with his theory; if all motion had to be caused by some force acting on it, then why do objects fall towards the earth when you release them from a fixed position? This free falling object was in fact free, meaning free of outside forces acting upon it (besides wind resistance). There were no visible forces acting upon that object. So why do they move downward if nothing is acting on it? But Newton explained this motion with gravity. He said that gravity is a force that the earth has upon all objects, something invisible that pulls us down at all times at a constant acceleration. There is a myth that the way Newton thought of the idea of gravity was when he was thinking about it under an apple tree when an apple fell on Newton’s head and at that moment, he figured out that there must be a force pulling the object down. This is also why apples are used to demonstrate Newton’s force, but no one knows definitively if the myth is true or not. Read the rest of this entry »

Leave a Comment » | College level, Elementary level, experiments, High School level, Middle School level, Physics | Tagged: acceleration, awesome experiment, force and motion, gravity, Newton's Apple, PBL, phenomenon based learning, phenomenon-based science, science, Sir Isaac Newton, spacetime | Permalink
Posted by Tami O'Connor

Talking Tapes | When You Want Your Students To Make Noise!

April 30, 2011

by: Tami O’Connor

On a field trip with my 5^th grade students to a local science museum, we saw one of the science instructors conduct a lesson on sound. It was such a simple idea, with easy-to-find materials, that I brought it home to do with my Girl Scout troop the following week. Since then, I have modified and expanded the lesson so it would fit any elementary or middle school grade lesson plan on sound.

Read the rest of this entry »

Leave a Comment » | Elementary level, energy, experiments, Middle School level, sound | Tagged: amplitude, awesome science experiment, easy-to-find materials, PBL, phenomenon based learning, phenomenon-based science, science, sound, sound experiments, vibration | Permalink
Posted by Tami O'Connor