Chemistry Experiment Cleaning Coins

Materials Needed:
Old Coins
1/4 Cup of white vinegar
1 Teaspoon Salt
Non-metal Bowl
Water

Objective:
Clean the old and dull pennies using vinegar to make them "blink" and shine again.

Procedure:
1) Pour the vinegar into the bowl and add salt.
2) Stir the solution.
3) Put 4-5 pennies inside the solution.
4) Wait for about 10 seconds.
5) Take the pennies out and rinse them in water.
6) Observe (You should be able to notice the coins become shiny again).

Reason:
Vinegar is an acid and reacts with salt to remove the dullness or remove copper oxide which was making the coin dull.

Now, some questions to ponder about...

1) Will other acidic stuff like lemon and orange work in this experiment?
2) Can this experiment be done on other old coins and work as well?
3) Does it matter if I add more salt or more vinegar in this experiment? Does it affect the results?

Reflections:

This experiment clearly shows the reaction between acid and salt- solution to removing copper oxide. This experiment is very useful and interesting as a teaching tool (if possible) as just talking about chemical equations in class can be very boring. Doing the experiments for the students to see, they could understand the lesson better. I hope to have more experiments in time to come, maybe to prove chemical equations or just to show students how the chemicals really react with each other. This kind of experiment would be able to capture the attention of the students, making it a fun learning experience for the students!\

Source: http://www.sciencebob.com/experiments/pennychem.php

First Post (Straw)

Experiment Materials Needed:
Straw
Water
Cup

Question:
Why doesn't the water in the straw "drop" when the straw is held in the air if I cover one of the opening of the straw?

Answer:
Air pressure is the main concept behind this. As air is a matter, it experiences gravity as well. Since gravity is strongest near the earth's surface, it holds the atmosphere which contains different types of air and is closest to the earth's surface. This pushing force of the air is called air pressure.

This experiment is to explore air pressure. As you hold your finger on the opening of the straw, the air in the straw could not escape. Air pressure is when air presses down on the Earth's surface. Therefore, when you hold one of the opening of the straw, the water would not drop down as it is "protected" from the weight of air, not experiencing air pressure. However, when you release the finger, there would be air pressure, pushing down the water into the cup.

Reflections/Learning Point:
Air pressure happens because air, which has mass, experiences the pull of gravity. This experiment clearly explains this to me through visually. It is a very good experiment to show air presssure in the simplest form. Another experiment to show air pressure would be the "killer straw" experiment. I feel that this experiment is very interesting and this experiment was done by me when I was an adolescent. I did this experiment unknowingly as I was playing with my straw and water then. I did not expect this to be able to enlighten me in the concept air pressure. I really like this kind of "learning from "life" experiments" style of learning!

Source: http://www.newton.dep.anl.gov/askasci/chem99/chem99313.htm

Introduction

Hi Guys! This shall be the platform where my Science E-portfolio would be at. Enjoy the posts!!