ts In a , there is a change in the way atoms and ncep Find these Co molecules combine. Signs of a chemical reaction include: color or temperature Words to Know in the word search below. change, or the production of light, electricity, or a new material.

matter - anything that fills space and has mass INDICATOR W ATOM atom - a very, very small particle that makes up all BASE LIGHT o matter BUBBLES MATTER r molecule - a small particle made of two or more CHEMICAL BOND MIXTURE d connected atoms CONCENTRATION MOLECULE CheM LaB ion - an atom or molecule with an electrical charge ELECTRON OMSI s electron - a negatively charged part of an atom ENDOTHERMIC REACTION chemical bond - formed when electrons are EQUILIBRIUM Take-Home Activities transferred or shared between two atoms EXOTHERMIC TEMPERATURE t chemical reaction - an interaction of atoms or o molecules to form new elements or molecules exothermic reaction - a chemical reaction that I E M E E L T W M K G W E C O gives off heat and that may feel hot S L B I S L O Q A U O V U I E k endothermic reaction - a chemical reaction that M E U T X A U J T A C I D M X n absorbs heat and that may feel cold O C B G H T B C T X H U F R O mixture - two or more materials that are mixed I T B N S G U Y E M X K A E T o together but not chemically bonded w solution - a completely uniform mixture Q R L A E J I R R L S T I H H concentration - the relative amount of a particular F O E A S L D L E F O O X T E atom or molecule in a solution. A large amount is W N S K G E G A A M M M N O R a high concentration; a small amount is a low C O N C E N T R A T I O N D M concentration M F E Q U I L I B R I U M N I acid - a compound that increases the number of I N D I C A T O R T C M K E C hydrogen (H+) in solution with water. All S O L U T I O N C B C A E D M have a pH below 7. B O N D N O B L A C I M E H C base - a compound that decreases the number of H O R N G C E I O N I M E Q C Chemical hydrogen ions (H+) in solution with water. All bases have a pH above 7. E R U T A R E P M E T V H K G pH - a scale that measures relative acidity and basicity Reactions indicator - a chemical that changes color with changes in pH. equilibrium - a point reached during a chemical reaction when no further changes occur This project funded by

© 2006 OMSI Cloudy Globs Glow Fast, Glow Slow Gas Production

Can you make a white gel from two clear liquids? Alter the rate of a reaction! Blow up a balloon! Materials: Materials: Materials: two small jars or glasses (about 4-oz) two clear glasses or jars baking soda warm water water tablespoon alum (in the spice aisle at grocery stores) ice one plastic bottle (1 liter or 20 ounces) 1/2 teaspoon measure two identical “lightsticks” small cup 1 teaspoon measure a dark room or area vinegar funnel To do and notice: one large balloon (8” or 9” size) To do and notice: 1. Run hot water from the faucet until it is quite hot. To do and notice: 1. Fill one jar half full with warm water. (Caution: be careful not to burn yourself.) Fill one glass 1. Measure 2 tablespoons of baking soda. Pour with the hot water. the baking soda into the plastic bottle. 2. Add ½ teaspoon alum. Stir or shake to mix the water and • What does the baking soda look like? alum completely. 2. Fill the other glass with ice and water. 2. Rinse and dry the tablespoon. Measure 3 3. To the other jar, add 2 teaspoons ammonia. tablespoons vinegar. Pour the vinegar into • What do the look like in each jar? 3. Activate both lightsticks by the small cup. • Are the solutions clear or cloudy? bending them until they snap and • What does the vinegar look like? ammonia then shaking them. 4. Pour the ammonia into the jar with • What do you observe? 3. Using the funnel, pour the vinegar into the balloon. water and alum. • What happens? 4. Put one lightstick in each jar. 4. Attach the lip of the balloon onto the mouth of the bottle. Be careful not to spill the vinegar. 5. Allow the jar with the new mixture to 5. Turn out the lights or take the jars to a dark room or lift sit for a while. closet. 5. After the balloon is attached, lift the • What do you see at the bottom of • Which lightstick is glowing brighter? water and alum balloon to dump the vinegar into the bottle. the jar? • Which lightstick glows longer? • What do you hear? • What do you see? A closer look: A closer look: • What is happening to the balloon? Alum dissolves in water to make a clear solution. Energy transfer is part of all chemical reactions. The Ammonia (NH ) reacts with water to make a clear A closer look: 3 reaction in lightsticks releases energy in the form of light. solution of hydroxide (NH OH), or household When you mix vinegar and baking soda, their molecules 4 This process is called “chemiluminescence.” ammonia. When you mix these two clear solutions interact and make new substances. together, they react to form a new compound. A temperature change can cause a chemical reaction to go Baking soda, also called bicarbonate, has the faster or slower. Heat speeds the rate of the chemical Alum contains aluminum When alum reacts with ammonia, formula NaHCO3. Vinegar, also called acetic acid, has reaction, so the lightstick in hot water is brighter. Cold aluminum hydroxide (Al(OH) ) is formed as a product of the formula CH3COOH. When they recombine they 3 slows the rate of the reaction, so the cold lightstick’s the reaction. Aluminum hydroxide does not dissolve in make sodium acetate (NaCH3COO), water (H2O), and supply of chemicals lasts longer. (Depending on the brand water and forms cloudy white globs. As the globs settle, carbon dioxide (CO2). you use, they may last 20 minutes to several hours.) they form a solid gel at the bottom of the jar. Carbon dioxide is the gas that creates bubbles inside © 2006 OMSI the bottle and inflates the balloon.