Introduction: The study of chemistry is vital to understanding the natural world around you. The principles of chemistry are at the heart of nearly every aspect of life that you perhaps take for granted, but nevertheless, depend upon every day. The agricultural, automotive, cosmetics, energy, food service, pharmaceutical, and plastics industries, just to name a few, are directly dependent upon an in-depth understanding of chemistry. New advances in chemistry will eventually have a positive impact on the quality of your life. Chemists will play a major role in finding ways to clean up the environment, develop alternative sources of fuel, and increase crop yields around the world. In addition to all of these practical benefits, chemistry is a fascinating subject, worthy of study for curiosity’s sake.
Chemistry is also an experimental science. Experimentation is the key to discovery and valid experiments depend on accurate measurements and detailed observations. Therefore, we will be focusing on measurement and observation techniques in our first unit. One of the main objectives of this course is for you to develop the thinking skills and habits of a scientist. Here is a partial list of some of these characteristics.
Pay attention to detail.
Are careful to record their observations and results
Look for connections.
Never stop asking questions.
Are not afraid to try new things.
Talk to other scientists about their results and ideas.
The laboratory activities in this unit are designed to challenge you to utilize these skills. As the year goes on, you will need to employ these skills in order to succeed in this class, and hopefully you will utilize them for the rest of your life.
“The most important of my discoveries have been suggested to me by my failures.” ~ Sir Humphrey Davy
Lab #1 Observations of a Burning Candle “The Greatest enemy of knowledge is not ignorance, it is the illusion of knowledge.” ~Stephen Hawking
Objectives: To improve your observation skills.
To learn to ask questions that lead to discovery.
To develop a hypothesis of the process of the burning of a candle based on evidence derived from your observations.
Light a candle and record your observations with as much detail as you can. Here are some suggestions to help you observe more thoroughly: What are the colors of the flame? What is the shape of the flame? Is the candle’s flame hollow? What is the color and shape of the wick? Does the wick give visible evidence of being hot? Does the wick get longer as the candle wax is consumed? Is the wick combustible? Does the wick burn right at the surface of the candle wax?
Part B - What’s in a Flame?
Blow gently at the candle flame through a horizontal straw that is held about one inch from the flame. Start at the top and work down. What do you see? Record your observations in the form of several labeled diagrams. You may want to include this method of recording observations throughout this lab.
Observations: Part C – Where There’s Smoke!
Blow out the flame. What do you see? Describe the smoke. From what part of the candle does the smoke originate? What is the last site of smoke generation? Hypothesize as to the composition of the smoke. What other event(s) occurs with the cessation of smoke generation?
Relight the candle and allow it to burn for about a minute. With a lighted match in one hand, blow out the candle and hold the burning match in the rising column of smoke about an inch above the candle’s wick. What happens? Does this support your hypothesis about the composition of the smoke?
Part D – Scorch Marks
Move a horizontally held notecard (that has been moistened with water on the underside) quickly down over the flame to a height where the card almost touches the wick. Hold the notecard in this position just long enough for the flame to scorch through to the upper side of the card, but not long enough to cause it to burst into flames. (If the card begins to burn, toss it into the sink and run water to extinguish the flame.) Draw a pattern of the scorched area on the top of the card. Note the shading.