Types of Chemical Reactions Lab Date(s)

Transcription

1 Types of Chemical Reactions Lab Date(s) (don t forget to put the title/page # in the Table of Contents) Lab Partner: Purpose : (Read through the info for each station, then write 2-complete sentences stating the purpose of the lab.) Station 1 (Combustion of Sulfur-Step 1 of Making Acid Rain): When crude oil is pulled from deep underground it has a lot of other stuff besides the hydrocarbons needed to make gasoline. Sulfur is one such element that is trapped up in the crude. If the concentra on of sulfur is greater than.5% it is called Sour Crude Oil and the sulfur must be removed otherwise it ends up in the atmosphere and makes sulfuric acid rain. Once the sulfur is below.5% the refinery calls it Sweet Crude Oil and can then use it to make gasoline. Station 2 (Reacting Acids & Bases to make Salt & Water): O en reac ons are observed not by drama c changes in color or gaseous produc on, but through evidence of bond restructuring with associated energy changes. Station 3 (Pop Goes the (Hydrogen) Weasel): Hydrogen gas is combus ble so it could be used as a fuel in cars, houses, etc. But, it is also hard to contain and takes up a lot of space. The great thing is that it is easy to isolate hydrogen as a gas from other materials such as metals and acids! Station 4 (Making Limestone from Liquids): Limestone is a sedimentary rock that forms at the bo om of oceans as shelled organisms decay. The shells are full of calcium carbonate which solidifies into limestone. The great pyramids of Giza in Egypt, Lincoln Memorial in D.C. and the Empire State Building (facade) in New York are all made of limestone. Station 5 (Rapid Rust): It is es mated that corrosion from rust costs the US $500 Billion per year! Oxygen greedily a acks the iron in steel and steel is one of the most widely used materials in our lives. From buildings, to cars, to railroads and everything in between, humans are in a constant ba le to protect steel from rus ng because the rust ul mately destroys the steel. This oxida on of iron is also what makes the planet Mars look red due to the mar an rock having high concentra ons of iron. Station 6 (Catalyst-speeding up reactions): Hydrogen peroxide H 2 decomposes naturally but it is very slow. A catalyst is something that speeds up or slows down a reac on. Station 7 (Ping Pong Pop): Some reac ons are explosive. When the combus on reac on proceeds, it releases energy in the form of heat and light and makes gases. This energy, along with the forma on of gases causes the volume of the products to be greater than the reactants (they take up more space - hot air takes up WAY more space than a liquid). This change in volume results in an increase in pressure. We can use this concept to make a ping pong pop gun.

2 Background/Safety Concerns : (For each station, write the safety concerns expressed below.) Station 1 : Be especially careful hea ng the sulfur in the spoon and be sure to turn on the hood by flipping the big switch labeled Blower. Station 2 : Corrosive acid and base, wash immediately with water and let me know if you get either on you. Station 3 : Corrosive acid, wash immediately with water and let me know if you get it on you. Station 4 : Wash off both solu ons well with water if in contact with your skin. Station 5 : Be especially careful while hea ng the steel wool. Station 6 : Wash off solu on if in contact with skin. Station 7 : Methanol is highly flammable! Always put the top on the container. Do not use too much. Make sure the red bulb is cool before adding more methanol. Pre-Lab Questions : (Answer in complete sentences) Define exothermic and endothermic. List the five pieces of evidence for a chemical reac on. Station 1 : Write the chemical formula for sulfur dioxide. What is the molar mass of each of the following: sulfur, oxygen gas, and sulfur dioxide Station 2 : Define acid. (scien fically what is it? Don t define using the ph scale.) Define base. (scien fically what is it? Don t define using the ph scale.) Write the chemical formulas for hydrochloric acid, sodium hydroxide, sodium chloride and water. What is the molar mass of each of the following: hydrochloric acid, sodium hydroxide, sodium chloride, and water Station 3 : Write the skeleton equa on for: Magnesium (s) + Hydrochloric Acid (aq) Magnesium Chloride (aq) + Hydrogen (g) 2

3 Balance the skeleton equa on. One of the products is hydrogen gas. In this sta on, you will be pu ng a flame near the test tube to combust the hydrogen gas that is produced. Write the skeleton equa on for: Hydrogen (g) + Oxygen (g) Water (l) Balance the skeleton equa on. Station 4 : What is chemical formula for limestone? Station 5 : Write the skeleton equa on for the following: Steel wool (Iron) reacts with oxygen gas to form solid Iron (III) Oxide. Balance the skeleton equa on. Station 6 : Define catalyst. What is the catalyst in the reac on? Write the chemical formula for hydrogen peroxide. What is the molar mass of hydrogen peroxide? Station 7 : Write the skeleton equa on for the following: Methanol (CH 3 OH) reacts with oxygen gas to form carbon dioxide gas and water vapor. Balance the skeleton equa on. What type of reac on is represent? Procedure : (For each station, write one to two complete sentences summarizing the procedure.) Station 1 : Materials: Sulfur, deflagra on spoon, bunsen burner, matches, metal can, fume hood 1) Get a small scoop of sulfur in the deflagra on spoon 2) Light the bunsen burner 3) Close the fume hood as much as possible and place the spoon in the ho est part of the inner-blue cone bunsen burner flame - heat un l the sulfur begins to burn 4) Turn on the fume hood to remove all toxic fumes and con nue to observe the reac on 5) Open the fume hood slightly to view the reac on. Record your observa ons 6) Put the remains in the metal can and clean the spoon well in the sink 3

4 Station 2 : Materials: 6M HCl, 3M NaOH, test tube, test tube holder 1) Place 15 drops of 6M HCl in a clean, dry test tube 2) Add 15 drops of 3M NaOH to the same test tube 3) Feel the test tube, has the temperature changed? (Data) 4) Was energy absorbed or released by the reac on? (Data) 5) Pour the test tube contents down the drain with excess water and rinse the test tube three mes with water Station 3 : Materials: Mg ribbon, 3M HCl, test tube, wood splint, matches, metal can, ruler, scissors 1) Clean and dry a test tube 2) Add a 1 cm piece of Mg ribbon to the test tube 3) Quickly add enough 3M HCl (drops) to cover the strip of Mg ribbon 4) Hold a finger over the test tube to trap the gas that is produced and slightly swirl the test tube 5) Have your partner light a splint and insert the splint into the test tube 6) The final two steps may be repeated by placing a finger over the test tube again 7) Let the reac on sit un l all the Mg is gone. Pour the contents into the sink and grab any remaining Mg with a paper towel, dispose in trash. Rinse out the sink with excess water and scrub the test tube with soap and water. Station 4 : Materials: Na 2 CO 3 solu on, CaCl 2 solu on, test tube, test tube rack 1) Add 15 drops of calcium chloride solu on to a clean and dry test tube. 2) Add 15 drops of sodium carbonate solu on to the same test tube. 3) Flick the test tube to mix the contents. 4) Observe and record. 5) Pour the contents of the test tube into the waste jar at the sta on. Scrub the test tube with soap and water. Station 5 : Materials: steel wool, bunsen burner, matches, metal can, crucible tongs, lab tray 1) Remove a small piece of steel wool from the wool pad on the lab bench. 2) Pull it apart so that the wool strands are loosely separated. 3) Place the bunsen burner on the lab tray to keep pieces of steel wool from falling on the countertop 4) Use crucible tongs to hold the steel wool in the ho est part of the inner-blue cone bunsen burner flame (Fe will form a 3+ charge as a product) 5) Place all contents in the metal can and rinse off the tongs 4

5 Station 6 : Materials: 3% H 2, Mn solid, test tube, test tube holder, wood splint, matches 1) Place 2 dropper fulls of 3% H 2 in a clean and dry test tube 2) Add a small amount of Mn to the test tube 3) Record what is happening a er the introduc on of this catalyst 4) Feel the test tube, has the temperature changed? (Data) 5) Hold a finger over the test tube to trap the gas that is produced and slightly swirl the test tube 6) Have your partner light a splint, blow it out, and insert the splint into the test tube 7) The final two steps may be repeated by placing a finger over the test tube again. 8) Pout the test tube contents down the drain with excess water and scrub the test tube with soap and water. Station 7 : Materials: Ping Pong ball, dropper of methanol, Ping Pong Popper 1) Check to be sure the red bulb of the popper is cool (use your hand) 2) Look inside the red bulb and very quickly spin the brass handle CLOCKWISE to see if you can make a spark. You will need to spin it extremely fast, like snapping your fingers 3) Blow into the red bulb to be sure some oxygen will be present for the reac on 4) Drip 10 drops of methanol into the bo om of the red bulb 5) Place a ping pong ball in the opening so it is firmly held inside, not too far but not res ng on the top 6) Do not point the ball at anyone at any me 7) Do a countdown from 10 to 0 like they do at NASA. At zero yell, Blast Off! and spin the sparker 8) Immediately blow into the bulb to put out the flame 9) Do not add anymore methanol - it could explode!! Put all materials back into place Data/Observations : For each station, record all data and observations. All information is important and relevant. Write down anything you see, smell, hear, or measure. 5