Make Some RUST!

EQUIPMENT:

1. A clean steel wool
2. Tap water
3. Vinegar
4. Salt water
5. Three paper cups

INSTRUCTIONS:

1. At first cut out the steel wool into three pieces.
2. Then place each piece in a paper cup.
3. Fill one cup with enough tap water to submerge the piece of steel wool.
4. Then fill the 2^nd cup with salt water to submerge another piece of steel wool.
5. Again fill the last cup with enough vinegar to submerge the piece of steel wool.
6. Examine the three submerged pieces of steel wool after fifteen minutes.
7. Record any kind of changes.
8. Examine the pieces of steel woo after 2 hours.
9. Record if there is any change.
10. Examine the pieces of steel wool once a day for about 3 or 4 days.
11. Record any kind of change you observe.

RESULTS:

1. A brown layer of rust is developed on all the pieces of steel wool over time.
2. The piece of steel wool which was in the vinegar starts to show signs of rusting almost immediately.
3. The steel wool piece that was in the salted water shows signs of rusting within a couple of hours.
4. The steel wool piece that was in the tap water starts to rust in about 3 days.

EXPLANATION:

Steel wool is made of iron. When iron reacts with the oxygen in the air a substance called iron oxide is created. It’s commonly known a rust.

The reaction is :

Rust form through Chemical Reaction

For the reaction to happen, some of the iron metal becomes iron ions in a process called ionization. Ions are electrically charged atoms which have changed chemically to either loose or gain electron. Iron metal can slowly ionize in the water. That’s why wet iron rusts. The iron ions can react with the oxygen dissolved in the water to create iron oxide. However, in salt or acidic solutions, the ionization process is a lot quicker.

In this experiment naturally the salted water is a salted solution. The presence of salt in the water boosts up the ionization process of the iron enough to make the rust visible within a couple of hours or a bit more. However, the vinegar is way better at ionizing iron. Vinegar is actually acetic acid. It can make iron oxide appear on iron within a few minutes.

MORE EXPLANATION:

The chemical reaction which causes the rust to form on iron is actually a type of corrosion. It’s the equivalent of the chemical reaction that causes green layer to appear on American pennies or copper. (To know more about this, you can read the experiment Make your coins green!) The only difference is that while pennies corrode and copper oxide is formed, the layer of copper oxide actually protects the metal underneath. But on the other hand, iron oxide destroys iron metal over time and make it fragile and useless.

MORE EXPERIMENTS FOR YOU: 

1. Use other kinds of acids to see and compare the effect.
2. Use sugar water to see the effect!
3. Can the rust be dissolved using other kinds of acids?

How to do electroplating?

MATERIALS :

1. An iron nail or brass key
2. Dish soap and steel wool
3. A plastic container
4. Vinegar
5. Insulated copper wire (Can be obtained from a hardware or electronic store)
6. A strip of copper (Can be obtained from a hardware or electronic store)
7. Wire strippers (Can be obtained from a hardware or electronic store)
8. A six volt battery

INSTRUCTIONS :

1. At first clean the iron nail or brass key with dish soap and the steel wool.
2. Then pour some vinegar into the plastic container.
3. Now add some salt in the vinegar and mix it well to make it dissolve.
4. Now make an edge of the copper strip bend so that it hangs over the edge of the plastic container.
5. Cut 2 pieces of insulated copper wire. Each piece of wire should be the length of about a foot.
6. Strip both ends of each of the wires.
7. Now wrap one end of one of the copper wires around the copper strip and wrap the other end around the positive terminal of the six volt battery.
8. Then wrap one end of the 2^nd wire around the iron nail or brass key and wrap the other end around the negative terminal of the six volt battery.
9. Hang both the copper strip and the other object inside the plastic container. Make sure that both objects are particularly submerged. Also make sure that the opposite wires and the objects do not touch one another.
10. Now observe what happens to the objects in the next one hour.

RESULT :

1. After fifteen to twenty minutes the iron nail or the brass key should start to look a bit coppery.
2. The iron nail or the brass key should be totally copper plated at the end of one hour.
3. The copper strip should also change over time. When the copper strip is removed from the vinegar salt mixer or bath it feels quite brittle.

EXPLANATION :

In our experiment when current passes through one metal loses electrons while the other metal gains that electron. The two different metals used in this experiment have different tendencies towards losing electrons. In our experiment Copper has much more tendency to lose electrons than iron or brass. That’s why copper is said to be the more active of the metals. The more active metal of the two acts as the anode and the less active metal acts as a cathode in an electroplating. But just losing or gaining electrons doesn’t actually explain how a layer of metal is transferred from one metal to another during electroplating. When the copper strip loses electrons copper ions are formed in a process which is called ionization. These copper ions are dissolved into the electrolyte which is the vinegar and salt mixer or bath in our experiment. At the cathode which is the iron nail or the brass key, positively charged ions can gain electrons. The metal in the iron nail or brass key didn’t get ionized so the only metal ions available to gain electrons are the ions of copper in the electrolytic bath i.e. the vinegar and salt mixer. When the copper ions gain electrons they once again become copper atoms. Because this process actually occurs in the cathode, the copper atoms deposited there. Over time a layer of copper will coat the cathode which is actually an iron nail or a brass key.

The reason for the copper strip becoming more brittle after the electroplating is finished is because this process actually takes copper out of the anode and deposits them on the iron nail/brass key/cathode. The longer the process of electroplating or copper plating is continued the the more the copper would dissolve and become more brittle.

MORE EXPLANATIONS:

Electroplating is really very important in our modern everyday life. You may not know but it is used in variety of ways. Cheap jewelry is electroplated with gold to make it look much more valuable. Car parts made with steel are electroplated with nickel. This provides the car parts protection from rust and corrosion. Also after electroplating with nickel the car is covered with chrome with this process to make the car look nice and shiny. Even the wristwatch, which are made of metal are electroplated for long lasting effects.

MORE EXPERIMENTS FOR YOU :

1. Use nickel strip instead of copper strip.
2. Do this experiment with copper at first and then replace the copper with nickel. Also leave the copper plated iron nail or brass key or the cathode in the electrolyte. After that do the same experiment with this. Nickel is actually much more active metal than copper. So observe if you get another layer of coat on the cathode or not?