In life, we often ignore the safety of some daily necessities, such as cups for drinking water. Drinking hot water is a habit in many families, but some cups may release harmful substances when filled with boiling water, slowly "poisoning" our body.
Today, we will talk about which cups are not suitable for boiling water from the perspective of junior high school chemistry, and the scientific principles behind them.
Enamel cups with paint peeling
The main component of the enamel cup is metal, and the surface is covered with an enamel coating.
The purpose of this coating is to protect the metal from rust or oxidation in contact with water or air.
However, if the cup bumps off the paint, the metal inside is exposed, especially metal materials such as aluminum and iron may undergo chemical reactions at high temperatures, releasing heavy metal ions.
According to the principle of metal oxidation in junior high school chemistry, these heavy metal ions can pose a potential threat to human health after long-term consumption after dissolving in water.
Therefore, the enamel cup is no longer suitable for holding boiling water after the paint is removed.
Glacier cups in color
Glacier cups are popular because of their aesthetically pleasing colors, especially those with gradient colors.
However, the color of most glacier cups is applied to the surface through an electroplating process, and the chemicals in the coating may react with water at high temperatures, releasing harmful metal ions.
This is similar to the principle of "galvanic corrosion" that we learned, where high temperatures accelerate the decomposition of the coating, causing harmful substances to enter the water.
To be on the safe side, it's best to choose a colorless glacier cup, or simply use a clear glass.
PC "potbelly cup"
PC plastic cups (polycarbonate) are lightweight and easy to use, but at high temperatures, their structure may change, releasing a chemical called bisphenol A (BPA).
Bisphenol A is an environmental hormone that can interfere with the body's endocrine system and affect growth and development when exposed to it for a long time.
According to the knowledge of polymer compounds in junior high school chemistry, PC materials are polymers synthesized from phenolic compounds, which are prone to chemical degradation under high temperature conditions.
Therefore, the cup made of PC material is only suitable for cold water, and should never be used to hold boiling water.
Ordinary plastic cups are prone to decomposition at high temperatures, especially low-quality plastics.
In junior high school chemistry, we learned that plastic is a polymer material, and long-term high temperature will cause its structure to be unstable and decompose small molecules of harmful substances, such as benzene compounds and bisphenol A.
Once these compounds enter the body, they can interfere with hormones and even increase the risk of cancer.
For safety, it is recommended to use food-grade plastic cups (such as PP) that are resistant to high temperatures, or simply use glass or stainless steel cups.
Unqualified stainless steel cups
Although stainless steel cups are durable, if you choose an unqualified material, it will still bring hidden dangers when you use it.
The chemical stability of stainless steel depends on its composition, and junior chemistry tells us that the nickel and chromium elements contained in stainless steel can prevent corrosion and rust, but only food-grade stainless steels like 304 and 316 are safe.
If inferior stainless steel materials are used, not only can not achieve the anti-rust effect, but also may release heavy metal ions, which will cause chronic damage to the human body for long-term use.
Therefore, when buying stainless steel cups, you must pay attention to whether the food-grade material is marked.
How to choose a safe cup?
Starting from the knowledge of chemistry in junior high school, you can refer to the following points when choosing a safe cup:
1. Prefer glass and stainless steel cups.
Glass is a non-metallic material with stable chemical properties and will not react with hot water; Stainless steel needs to choose food grade.
2. Avoid cups that are too brightly colored.
These colors are likely to contain heavy metal substances that release harmful substances at high temperatures.
3. Use and clean the cup properly.
Even cups made of safe materials should be cleaned frequently to prevent the growth of bacteria.
A small cup may hide a lot of chemical knowledge, and it is also related to our health. We should not only pay attention to the appearance of the cup, but also pay attention to whether its material is safe.
The next time you use the cup, don't forget to check to see if it meets the health standards.
For the health of yourself and your family, hurry up and check the cups at home and replace those that are potentially dangerous!
I hope this article can help you learn more about chemistry in your daily life and protect the health of your family.
If you have any other questions or want to know about chemistry, please share them in the comment area!