Can't Judge A Powder

Basic Info
Can't Judge a Powder is a chemistry event. The goal is to teach Science Olympians about the importance of observation of many things in a short period of time. Normally you get 25-35 minutes of using different substance and observe the reaction of the powder that the event coordinator provides.

What You Need to Know
You should have a understanding of different types of reactions ie. chemical and physical. Also know how to use the lab equipment safely.

Observations versus Inferences
Observations versus Inferences An observation is the gathering of information by using our five senses: sight, smell, hearing, taste, and touch. There are two types of observations, qualitative and quantitative. Qualitative observations describe what we observe, such as the sky is blue. Quantitative observations measure what we observe, using numbers, such as the flower has seven petals. Both types of observations are necessary for this event. An inference is an explanation for the observation that you have made. They are based on previous experiences and prior knowledge. While these are important, during a competition you only want to make observations in order to receive the most credit for you answers.

Please note that this table is only showing the ideas behind observations and inferences. The wording of the phrases is made simple to get the point across, but these observations are not quality, and would not receive a 5 on a test. -Some judges will consider the pH value, based off a chart, to be an inference, while others will consider it an observation. This response was given to a rules clarification asked on this topic- "I would think that if you are given a key or color chart for the pH paper then the student should record both the color and the appropriate pH. I very often use wide range pH paper. If I asked this question at the National Tournament, I would score 5 points for color and pH and only 4 points for just one or the other."

Practice: Label each of the following observation or inference.
 * 1) The powder dissolves in water.
 * 2) The powder is acidic.
 * 3) The powder is soluble in HCl.
 * 4) The powder conducts electricity when dissolved in water.
 * 5) The pH paper becomes amber when dipped into a solution of the powder.
 * 6) The conductivity tester lights up when dipped into a solution of the powder.

Process for Making Observations
This is an event where you are required to make a large number of observations about a sample in a short period of time. The best way to do this effectively is to have a system that you use every time you practice and compete so that you are able to work quickly. You will almost definitely only have 1 pen for each section, so get used to having one person do tests and the other write down observations. If you are using enough detail in your observations, that person writing will likely be significantly slower than the person doing the tests with the powder.

An example of a process is this:

Person 1- Person 2-
 * Make observations about all of its physical properties.
 * Start by taking the mass of a beaker (or other measuring device), alone, if you are given a balance.
 * Using the same beaker (measuring device), take the mass of the a certain amount of the powder (be sure to record this).
 * i.e.[20 ml of the powder in the beaker weighs 500 g]

(After both are done) One person writing on sheet while other is performing tests-
 * Distilled water alone
 * Powder and distilled water
 * HCl alone
 * Powder and HCl
 * NaOH alone
 * Powder and NaOH
 * Finish with whatever else they have you doing, it could be another solution to test with, or it could be certain experiments that you have to do.

Tips about making Observations

 * 1) Make observations, not inferences.
 * 2) Write down anything you see, whether it be a color change, or just that the HCl is 1M. The test can technically have questions about anything given to you, so even though making these observations may seem stupid, the more you write down, the more you will have to do the test with.
 * 3) Remember that density, solubility, and conductivity are all inferences based on something you observe, so write down what you see, not what you infer.
 * 4) Control observations are very important and appear on many tests. These can be anything from the amount of a substance given to its color, and are a good way to find out who actually knows what the event is about.

Links and Files
example of observation sheet

[[Media:Cant_Judge_A_powder_Coaches_Clinic.ppt| Can't Judge a Powder Coaches Clinic Power Point‎]]