Let’s dive into the topic of distilled water. You’ve probably heard that it’s pure, but have you ever wondered what its pH is? Is it neutral like we expect from pure water, or does something else affect it? Let’s break it down in simple terms.
What Exactly Is Distilled Water?
Distilled water is water that has gone through a special purification process called distillation. In this process, the water is heated until it turns into steam, leaving behind impurities, minerals, and other contaminants. That steam is then cooled down and collected as clean water. Sounds perfect, right? But how does this purity influence its pH?
The Ideal pH of Pure Water
First, let’s talk about pure water. Pure H₂O has a pH of 7, which is right in the middle of the pH scale. This means it’s neither acidic (pH below 7) nor basic (pH above 7)—it’s just neutral. This neutral state is because, in pure water, there’s a balance between hydrogen ions (H⁺) and hydroxide ions (OH⁻). When these two are in equal amounts, you get a pH of 7.
So, technically, if you had 100% pure distilled water in a vacuum, its pH would be exactly 7. But here’s where things get a little more complicated.
Why Distilled Water Isn’t Always pH 7
Distilled water doesn’t stay in that perfect state of neutrality for long. The moment it’s exposed to air, it starts absorbing carbon dioxide (CO₂). This CO₂ dissolves in the water and reacts to form carbonic acid (H₂CO₃). Even though carbonic acid is weak, it’s enough to shift the water’s pH away from neutral. As a result, distilled water that’s been sitting out for a while usually has a pH closer to 5.5 to 6.5.
This slight acidity happens because of this natural reaction with carbon dioxide. The longer the water is exposed to air, the more acidic it can become—but don’t worry, it’s still not harmful.
Does This Make Distilled Water Dangerous?
Not at all. The shift in pH doesn’t make distilled water unsafe to drink. It’s still used in laboratories and medical settings because it’s so clean. In fact, people use distilled water for all sorts of things, from making baby formula to filling car batteries. It’s considered safe for consumption, but since it’s stripped of minerals, it might taste a little flat compared to regular tap water.
So, What’s the Takeaway?
- Pure distilled water starts with a neutral pH of 7.
- When exposed to air, it absorbs carbon dioxide, lowering the pH to around 5.5 to 6.5.
- Despite this slight acidity, distilled water is still safe to drink and widely used for various purposes.
The next time you hear someone say distilled water is “pure,” you’ll know there’s a bit more to the story—especially when it comes to its pH!
Other related resources:
How to Calculate pH From Molarity?
Check it More Chemistry Guides
Leave a Reply