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Which of these are ways to write that which acidic solutions contain a lot of?


Do you want some lemon juice? Yuck, it's too sour! Of course it's sour! It contains a lot of acid - citric acid. Yes, that's why we add sugar to lemon juice.

It sort of... removes the acid. No it doesn't. The sugar only hides the sour taste. If I measured the acidity, it would be unchanged.

What are you talking about? If it doesn't taste acidic, it can't be acidic! No Michael, Jenny is completely correct. Our ability to determine acidity by taste can be fooled by sugar, but acidity is a chemical property. And there are other ways to measure it than using taste.

What is acidity, then? Let's look at some of the substances in lemon juice: A water molecule, and a molecule of citric acid. Did you see what just happened there? Something left the citric acid molecule and attached itself to a water molecule. Let's look at it one more time.

It's a hydrogen ion that moves from the acid molecule - to the water molecule. A hydrogen ion always attaches to another molecule, like water, but to simplify things, we often say that it just becomes a "free hydrogen ion", H-plus. And it's the number of these so-called "free hydrogen ions" - that determine the acidity. So if there are free hydrogen ions in the solution, it's acidic? It's not that simple.

Even in pure water, this happens. What? Did the water just break apart? Yes, even if the water is completely pure, some "free hydrogen ions" are formed when water molecules split up like that. But only one water molecule in six-hundred million does this.

That means that there are hydrogen ions in all aqueous solutions, even in pure water. If there are more hydrogen ions than in pure water - that is, a higher concentration of hydrogen ions - we say that the solution is acidic. The more hydrogen ions, the more acidic it is. Like the juice from a lemon. It has a concentration of hydrogen ions that is between ten thousand and a hundred thousand times higher than in pure water.

And that does not change if you put sugar in it. It'll still be just as acidic. Would you like some more hydrogen ions? Yes, but I think it's enough with the ones in the water here.