Discussion
After I’ve done the experiment, I clearly understand the concepts of physical change, successfully to identify if substances are performing chemical and physical change.
In this experiment, I think part A and C are physical changes. In part A of the experiment, I define it as a physical change because the product has shown the signs of physical change, because I’ve seen the particles flowing in the product, which means the product is a suspension and an indicator of physical change and the color of product is blue only. The product is a mixture, which means no new substance is formed, so it’s a physical change.
In part C, after I mixed the two reactants, it has no signs of chemical change in the product, and I can’t see any new substance has been formed, which is the best sign of a physical change. Also, diffusion occurs in the product, the sodium carbonate solution stays at the top and the copper (II) sulfate mixture stays at the bottom, so that I can sure it’s a physical change only.
For part B and D, I think they are chemical changes. In part B, when iron mixed with copper (II) sulfate mixture, the iron is dissolved in the product, which means a new substance is formed from iron, it’s a significant sign of a chemical change and the color has been changed to red, which is also a sign of chemical change.
In part D, when magnesium is put with hydrochloric acid, gas releases in the product, which is one of the most significant indicator of chemical changes and the solution fizzles, another sign of chemical change. The gas is a new substances produced from the reactants.
Even I saw quite a number of signs of different changes to prove the change in each observation. There are still some signs of physical and chemical changes that I didn’t see in this experiment, burning, and creation of precipitation are the two common signs of chemical changes that I haven’t used. State change, shape changes are also common and significant change of physical changes in experiments that I didn’t see.
Physical and chemical changes are very common in our life. But one thing is very important, physical change can be reversed but not chemical change. If you don’t believe me, do a simple experiment! Heat a piece of ice into water, and cool it back to ice! Ice becomes water, and water reverses to be ice. This simple experiment shows us the proof that physical changes can be reversed.
In our life, physical changes happen all the time, substances are mixed to become a mixture, coke is also a mixture and only physical change occur after the substance are mixed, which benefits us to have something that is so good to drink, and drinking is one most important activity in our life. Also, water changes its state if I heat or cool it, which also benefits us and important, if we want to have some cool drinks, just cool some water and turn it into ice and put the ice into the wonderful drinks.
Chemical changes also occur in our life. Oxygen reacts with metals; metals are worn by oxygen, which is very important and harmful to me because my properties that are made of metals will be damaged. Controlled burning in my body is also another important, beneficial chemical change in my body; new substances are formed from substances in my body and oxygen to maintain my life.
Conclusion
In conclusion, I think part A and C are physical changes, and part B and D are chemical changes. Also, I learnt how to recognize physical and chemical changes in this experiment, some chemical and physical properties of the substances used in this experiment and signs of a chemical and physical change.
Sources of error
Here is the list of errors:
- I couldn’t define the exact shape of copper (II) sulfate, which I might be wrong in the reactant description of part A about the shape of copper (II) sulfate.
Ways to Improve the Experiment
Here is the way to improve to the experiment:
- Use a magnifier to ensure the shape of the substances.
Applications of that Knowledge
After I learnt how to recognize chemical and physical change, I can check the milk in my refrigerator to see if the milk has chemical change, and I can drink it or not.
