Objective; Determine if water is a compound or element and explain your proof.

Chemist use a process called chemical analysis to learn about the nature and composition of the materials around us. While mixtures can be separated into their component parts by physical means, compounds must be broken down by means of a chemical reaction. Elements cannot be divided by any ordinary chemical means. Therefore, to find out if a substance is a compound or an element, you must carry out a chemical reaction. In the open ocean, salts will speed up the reactions with the addition of electrical conductance of water. (Chemical reactions must involve energy in the form of heat, light, or electricity.)

Elements react differently under certain conditions and scientist use this to help identify the specific elements in reactions. Oxygen does not burn, but a glowing wood splint will burst into flames when thrust into oxygen. Hydrogen burns with a colorless flame causing a popping sound.

Materials (not all items listed J)

6 volt battery

wires (2)

100g Epsom salts

two small test tubes

beaker

water

masking tape

Procedure (remember, if you repeat anything, document this!)

1. Fill beaker ¾ full with tap water, set aside

2. Connect one wire to the positive terminal, and the second wire to the negative terminal

3. Place the ends of this wire into the beaker and observe what happens.

a. What evidence do you see that a reaction is taking place?

b. Is the speed of the reaction the same for both electrodes?

4. Remove wires from beaker; measure out approx. 100 grams of Epsom salts. Add it to your water slowly while stirring. Stir until most of the mixture is dissolved.

5. Fill the two small test tubes with some of the water mixture. (It might be easier to do this with a pipette)

6. Disconnect one terminal of the battery and put the wire back in the beaker. Try to bend the wire so the exposed end is on the bottom of the beaker, but bent in a U shape with the raw end pointing up.

7. Place your finger over the open end of the test and invert it in the beaker; Once in the beaker, you can remove your finger and the solution should stay in place in the tube. Place it over the U shaped wire in the bottom of the beaker.

8. Do the same procedure (steps 6 & 7) for second wire.

9. Tape test tubes to side of beaker to stabilize them

10. Reconnect to the battery

11. Allow reaction to take place until gas replaces liquid in test tubes

12. Test the gas that was collected from the negative electrode first. Slowly remove the test tube from the beaker, keeping it vertical so that any remaining solution can drain into the beaker when it breaks the surface. Once this occurs, quickly place your finger on the open end of the test tube to keep the gas from escaping. Keep the tube upside down and your finger over the opening until you or your partner brings a lit match to the mouth of the test tube. Observe and record what happens.

13. Test the gas that was collected from the positive electrode. Remove the tube and drain any remaining solution as in step 12, but this time quickly turn the test tube right side up and cover the open end with your finger as you did before. Uncover the tube, and thrust a glowing splint in the open end. Observe and record what happens.