When brewed hibiscus first passes into solution (in other words, is extracted) dye. In a neutral environment, it has a blue color. Then, from the colors extracted acid, which changes the color of dye. Soda in solution creates a basic environment. In basic medium, the dye becomes dark blue. Adding vinegar again creates an acidic environment, and color is red.
As in the chemical substance is called altering the color in the presence of acids or bases?
Before giving the answer to the questions in the previous post. Invited all interested parties at home brew the infusion of hibiscus (also known as the Sudanese rose or hibiscus) and look closely at the process of brewing. It can be seen that the infusion of hibiscus first turns blue, and changes to red.
Sprinkle a little to the solution of baking soda. How to change the color?
To this solution, add a few drops of vinegar, look for a color change? How can we explain these observations?
Briefly escape from tedious calculations and think, is whether we use acids and bases in the home?
To do this, look at the main home chemical laboratory - the kitchen.
In the kitchen, many housewives have quite a lot of acid: vinegar (acetic acid), citric acid (or lemon juice in the bottle) as a minimum. What are they used?
Well, lemon juice is often added to tea. Many people like tea with lemon. And many paid attention that the addition of lemon juice into the tea, drink much lighter? And why is this happening? By the way, vinegar or lemon juice is added to some mistress soup in the first place due to the fact that the color of the soup becomes very beautiful.
And vinegar is added to preservatives. Why?
Is there any reason to the kitchen?
I suggest that you, fellow participants, look for answers to these questions.
Colleagues, well, first of all, I congratulate all of you on the beginning of the school year. Second, the beginning of autumn. So, soon the rains. And then it's time, it's time to rejoice-this. We will collect rainwater, measure its pH =). And there - and winter is not far off. We verify the acidity of snow.
The question then arises, and how to calculate the acidity of solutions of weak acids. In fact, because if the acid dissociates completely, then how do we know which molecules dissociate and what is not.
As we remember from chemistry course grade 7 (and someone probably read about it for the first time), the acid is a complex substance containing a hydrogen atom capable of substitution on the metal atom and the acid residue. It turns out that the ability to replace the hydrogen atom to the metal atom is linked to the process of dissociation. If we imagine that the acid is composed of n atoms of hydrogen and acid residue A, it turns out that these n hydrogen atoms by dissolving the acid in water, one detached from the acid residue A in the form of positively charged hydrogen ions (H +). Depending on the nature of the acid residue, the process may proceed to 100%, i.e. completely irreversible (and we are talking about strong acids), and it happens that it takes place completely. Then we are talking about weak acids
Alas, that the participants in this project is very small, and the conversation is not yet glued. Still, I very much hope that the project participants will join in the conversation, and we will launch a fruitful discussion.
So, in this project begin to appear the first results. I am very grateful to the children and their teachers, they decided to participate in this project. Initial support - it is very important. Thank you very much.