Science 1206 Core Lab #2 Chemical Reactions Page 1 of 5

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Mark Ellis
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1 Science 1206 Core Lab #2 Chemical s Page 1 of 5 Purpose : 1. To review nomenclature, balancing equations, reaction types, predicting products and evidence for chemical reactions 2. To improve observation skills and confirm phases of reactants and products Materials: Magnesium ribbon Candle 1 mol/l hydrochloric acid calcium metal zinc metal (mossy not powdered) solutions of: o lead (II) nitrate o sodium hydroxide o cobalt (II) chloride o sodium iodide o silver nitrate substitution of chemicals is possible please call in advance. Equipment: GOGGLES (must be on at all times) litmus paper (red and blue) or ph paper cobalt chloride test paper power source batteries or dc power pack electrolysis electrodes (paper clips will do) Bunsen burner (bic lighter should be sufficient) Small test tubes Small beakers Test tube holder Tongs or large tweezers Solution of sodium bicarbonate to neutralize any acid spills. Prelab Exercise: a) Identify and write down the reaction type for each reaction. b) Complete the balanced chemical equation, include predicted states of matter. c) Complete the word equation Procedure: 1. Describe the reactants before combining reactants (ie: color, state of matter ) 2. Follow the instructions for each reaction. 3. Goggles must be on at all times! 4. Describe the products after the reaction (ie: color, state of matter, heat/cool...) 5. Indicate the evidence of a chemical reaction a. A precipitate forms (new solid appears cloudy may settle to bottom) b. A color change c. An energy change (gets hot or gets cooler) d. A gas is produced (bubbles form) 6. Clean up and then move on to the next reaction.

2 Science 1206 Core Lab #2 Chemical s Page 2 of 5 Stations: #1 Example: {you can still do this one!) Pour about 2ml of dilute hydrochloric acid in a small test tube. Place a small piece of magnesium ribbon (1 cm) into the test tube. Place a cork into the test tube to trap gas. Using a glowing splint of wood quickly insert the splint into the tube. {usually only works once!} Single replacement Magnesium + Hydrochloric acid fi hydrogen + Magnesium Chloride Mg (s) + HCl (aq) fi H 2 (g) + MgCl 2 (aq) Shiny grey solid Colorless aqueous solution Colorless gas Colorless aqueous solution A gas is produced and some heat is produced. The magnesium disappears. Testing of the gas proved to be hydrogen {popping sound heard when ignited) #2 Adjust the Bunsen burner to obtain a blue flame. Using tongs or large tweezers hold a small piece of magnesium ribbon (3 cm) in the flame. Hold the magnesium over a large beaker. Do not look directly at the flame! {may need to clean off Mg with sandpaper or steel wool} Magnesium + oxygen fi + fi #3 Observe a burning candle. Hold a beaker full of cold water over the flame. Do not allow it to touch the flame or the beaker will get sooty and black, that is not what we are looking for here. If you have some cobalt chloride test paper hold it over the flame (do not catch it on fire). Be sure to clean the beaker. Candle wax + Oxygen fi + C 25 H 52 ( )

3 Science 1206 Core Lab #2 Chemical s Page 3 of 5 #4 Add a very small amount of calcium metal (no larger than the head of a match) to about 1 ml of water in a small test tube. Make sure you hold the test tube with a test tube holder, its going to get hot. Test the solution with some litmus or ph paper. Calcium + Water fi + + HOH (l) fi + #5 Add a few drops of silver nitrate solution to 1 ml of sodium iodide solution in a small test tube. Silver nitrate + Sodium iodide fi + #6 Add a small piece of mossy zinc (solid not powdered!) to about 2 ml of hydrochloric acid in a small test tube. Zinc + Hydrochloric acid fi +

4 Science 1206 Core Lab #2 Chemical s Page 4 of 5 #7 Adjust a Bunsen burner to a hot blue flame. Using tongs or large tweezers hold a small piece of steel wool in the flame. Be sure to observe the steel before and after. Iron + Oxygen fi + fi #8 Add a few drops of lead (II) nitrate solution to about 1 ml of sodium iodide solution in a small test tube. Lead (II) nitrate + Sodium Iodide fi + #9 Add a few drops of cobalt (II) chloride solution to 1 ml of sodium hydoxide solution in a small test tube. Cobalt (II) chloride + Sodium fi + Hydroxide

5 Science 1206 Core Lab #2 Chemical s Page 5 of 5 #10 Place two electrodes in a small beaker of water, don t let them touch. Apply an electric current using some batteries. (Check with your teacher to see if a power pack is available). Observe the surface of each electrode {it may take a little while}. water fi + fi + Questions: 1. In reaction #4, are the products acidic or basic? How do you know? 2. In reaction #9, how could you identify the two gases produced? Explain 3. What is a precipitate? Identify at least two precipitates in this lab. 4. State the law of conservation of mass. 5. Did you have your goggles on throughout this lab activity?

Classifying Chemical Reactions Analyzing and Predicting Products

Classifying Chemical Reactions Analyzing and Predicting Products Background A chemical reaction is defined as any process in which one or more substances are converted into new substances with different