13-3


 * Chemical Reactions Lab ** <---Previous Assignment - Next Assignment--->media type="custom" key="6581919"
 * __Instructions__ **
 * **Either put your observations on paper and turn in at the end of class or on a new page on your wiki titled 13-3 Chemical Reactions Lab.**

In this lab you will perform, record, and balance four different chemical reactions. Due to the hazards you **MUST** wear **Goggles.**
 * __Lab__ **


 * Reaction 1: Carbonic Acid Decomposition**

Fill a clean, **small** test tube about ½ full of carbonic acid. Place your thumb over the mouth of the test tube to seal it, and shake the test tube. Record your observations about the change in //pressure// you feel against your thumb.

Thoroughly rinse out the test tube and let it air dry in the test tube rack. Wash off your thumb.


 * Reaction 2: Combustion of Magnesium**

Get a wire gauze, and set it near a bunsen burner. Light a bunsen burner.

Obtain a piece of magnesium metal about the size of your pinky fingernail from your teacher. Make an observation about the //appearance// of the magnesium.

Hold one end of the magnesium with the **crucible tongs** (ones with no plastic) and place the other end of the magnesium into the flame of the burner until it catches on fire. **Then hold the magnesium over the wire gauze on the laboratory bench while it is burning**. Looking directly at the burning magnesium will cause vision problems.

When the magnesium is finished burning, place all the ash on the wire gauze. Make an observation about the new //appearance// of the magnesium ash.

Throw all the ash into the trash and gently shake off the wire gauze into the trash as well. Return the wire gauze to its drawer. Keep the Bunsen burner on, but be careful.


 * Reaction 3: Double Replacement Reaction Forming PBI2**

Fill a clean, small test tube about ¼ full with NaI (Sodium Iodide). Fill a second, clean, small test tube about ¼ full with Pb(NO3)2 (Lead (II) Nitrate). Make an observation about the //appearance// of each liquid.

Pour the test tube with NaI into the second test tube (the one with the Pb(NO3)2). Make an observation about the //appearance// of the new liquid and solid.

Thoroughly rinse out each test tube (the yellow solid can go down the drain) and let the test tubes air dry.

Read this whole section before beginning to get the best results
 * Reaction 4: Production of Hydrogen**

Get the beaker of HCl and take it to your station (return when done). Carefully fill a clean, small test tube about ¼ full of 1 M HCl over the sink and put it in your test tube rack. Wash your hands. Obtain a small piece of zinc from your teacher. //With the test tube in the test tube rack,// gently place the zinc piece into the HCl. Quickly, hold a second, clean, small test tube upside-down over the bubbling test tube. You are now trapping the gas inside the second test tube. After about **1 minute**, light a wooden splint with the laboratory burner, move the second test tube away from the bubbling test tube, but **//still hold it upside-down//**, and place the burning splint **//slightly//** in the mouth of the second test tube. A small pop will be heard (**don’t get scared** and drop the test tube – you’ll be fine!)

Blow out the burning splint, turn off the laboratory burner, and rinse out the two small test tubes with lots of water. If there is still any solid zinc in the test tube, catch it before it gets washed down the drain (have your hand really wet or use the tongs) and throw it away. Leave the test tubes to air dry and throw away the burnt splint. Tidy up your entire laboratory bench, wash your hands, and begin working on the questions on the next page.

For each of the reactions performed in the lab, balance the chemical equation.

Reaction 1 (12pts) Carbonic acid decomposes to yield carbon dioxide and water.

H**2**CO**3** à CO**2** + H**2**O

Reaction 2 (12pts) Magnesium burns with oxygen to yield magnesium oxide.

Mg +O**2** à MgO

Reaction 3 (12pts) Sodium iodide and lead(II) nitrate yield lead(II) iodide (yellow solid) and sodium nitrate.

NaI + Pb(NO**3**)**2** à PbI**2** + NaNO**3**

Reaction 4 (12pts) Zinc and hydrochloric acid yield hydrogen (the popping gas) and zinc chloride.

Zn + HCl à H**2** + ZnCl**2**

List four of the many different things you observed in this lab that would indicate a chemical reaction occurred. (12pts)