Color indicators. Change in color of acid-base indicators

What are indicators for?

Initially, the property of these compounds to change color in different environments was widely used to visually determine the acid-base properties of substances in solution, which helped to determine not only the nature of the environment, but also to draw a conclusion about the reaction products formed. Indicator solutions continue to be used in laboratory practice to determine the concentration of substances by titration and allow one to learn how to use available methods in the absence of modern pH meters.

There are several dozen substances of this kind, each of which is sensitive to a rather narrow area: usually it does not exceed 3 points on the information content scale. Thanks to such a variety of chromophores and their low activity among themselves, scientists were able to create universal indicators that are widely used in laboratory and industrial conditions.

How to Activate the Notification Light Using Always On Edge on Samsung Galaxy S10 Plus

Always on Edg

Step 2 When you open the app, you can see a list of settings from which you can select the notification LED you want.

note

It's important to remember that you need to grant the necessary permissions for the app to work. Step 3 Below you can see a list of alternatives with this in-app notification light

The list is quite broad, but the following can be highlighted:

Step 3 Below you can see a list of alternatives with this notification light in the app. The list is quite broad, but the following can be highlighted:

Put Led on camera or screen

With this option, you can choose whether the notification light will be around the screen or in the camera slot.

Change notification style

You can choose between different existing Led modalities, so the design style can be different

It is important to emphasize that the appearance can be changed in space or angles

Change LED notification color

This alternative is quite dynamic and fun since it allows us to choose the color of the LED lighting, here you can choose from a varied palette of colors to be able to customize up to 3 of these colors. With this tool you can edit and control the speed or thickness of edges.

Select when the LED will turn on

With this option we can decide when we want the indicator to be on, that is, we can choose, for example, not to show the indicator while the phone is charging or to only turn on when a notification is received. Even if we like it practical, we can set it to automatic mode so that it turns on the light when the device is locked.

With these two procedures, you can activate the notification LED all over the screen or around the camera notch of your Samsung Galaxy S10 Plus device.

Most used pH indicators

It is noteworthy that in addition to the identification property, these compounds have good coloring ability, which allows them to be used for dyeing fabrics in the textile industry. Of the large number of color indicators in chemistry, the most famous and used are methyl orange (methyl orange) and phenolphthalein. Most other chromophores are currently used in mixtures with each other, or for specific syntheses and reactions.

FLUORESCENT INDICATORS

Some chemical compounds, when exposed to ultraviolet rays, have the ability, at a certain pH value, to cause fluorescence of a solution or change its color or shade.

This property is used for acid-base titration of oils, cloudy and highly colored solutions, since conventional indicators are unsuitable for these purposes.

Work with fluorescent indicators is carried out by illuminating the test solution with ultraviolet light.

Methyl orange

Many dyes are named due to their primary colors in a neutral environment, which is also inherent in this chromophore. Methyl orange is an azo dye that has a group – N = N – in its composition, which is responsible for the color of the indicator turning red in an acidic environment, and yellow in an alkaline environment. Azo compounds themselves are not strong bases, but the presence of electron-donating groups (‒ OH, – NH2, – NH (CH3), – N (CH3)2, etc.) increases the basicity of one of the nitrogen atoms, which becomes capable of attaching hydrogen protons in a donor manner. acceptor principle. Therefore, when the concentrations of H+ ions in the solution change, a change in the color of the acid-base indicator can be observed.

Is the notification indicator important to you?

Facebook Twitter VKontakte Google+

It happens that you communicate with other people and find out that some functions in a smartphone that are completely insignificant for you can be very important for someone else. One such feature is an indicator light.

I myself hardly pay attention to this function, there is an indicator - good, no - and God be with it. What is this connected with? The fact is that manufacturers have almost stopped installing high-quality large light indicators in smartphones; it’s just some kind of nightmare. Instead of a large, clearly visible “circle”, as was the case in the Samsung Galaxy S3, they install tiny, barely visible “dots” that you can barely see in the dark.

Another problem with the indicator light is how it reacts to all app notifications. It happens that some uninformative message has arrived, for example, information that applications from Google Play are ready for updating or have already been updated, but the indicator is still blinking. My smartphone is always next to my computer, so the constantly flashing LED is quite annoying.

Or let's take another example: you put the device on charge at night and go to bed. Of course, in a dark room the indicator will glow red or green! Of course, you can install the Flow application and try to configure its operation yourself, but, according to reviews from my friends, this program does not work correctly on all smartphones.

But my opinion is not shared by all users, for example, my friend, on the contrary, really appreciates the presence of the indicator, says that many notifications come in a day, he does not always record them, and when he sees a flashing diode, he immediately understands that there is a missed message or call.

What do you think about this small but important element in a smartphone? Is its presence critical or, on the contrary, do you try to turn it off whenever possible? By the way, among the interesting solutions regarding the indicator, I can cite the example of Umi IRON Pro, in which this element was moved down

Learn more about making methyl orange

Methyl orange is obtained by reaction with diazotization of sulfanilic acid C6H4(SO3H)NH2 followed by combination with dimethylaniline C6H5N(CH3)2. Sulfanilic acid is dissolved in a sodium alkali solution by adding sodium nitrite NaNO2, and then cooled with ice to carry out the synthesis at temperatures as close as possible to 0°C and hydrochloric acid HCl is added. Next, prepare a separate solution of dimethylaniline in HCl, which is poured cooled into the first solution to obtain a dye. It is further alkalized, and dark orange crystals precipitate from the solution, which after several hours are filtered and dried in a water bath.

Circuit operation

I’ll briefly tell you about the purposes of the parts. Using R2 we adjust the input signal level. Through capacitor C1, the signal goes to the base of transistor VT1, which serves as an amplifier. Resistor R3 sets the bias to the base of the transistor. Then the amplified signal “comes” through capacitor C2 to diodes VD1 and VD2.

The negative signal goes to the minus, the positive signal to the 5th leg of the microcircuit. C3 and R4 serve as a filter. The higher the voltage on leg 5, the more LEDs light up. By the way, if you short pin 9 to positive, the LEDs will light up linearly. In the video you can see how this thing works.

Phenolphthalein

This chromophore got its name from adding the names of two reagents that are involved in its synthesis. The color of the indicator is notable for its color change in an alkaline environment with the acquisition of a crimson (red-violet, crimson-red) hue, which becomes discolored when the solution is strongly alkalized. Phenolphthalein can take several forms depending on the pH of the environment, and in strongly acidic environments it has an orange color.

This chromophore is obtained by condensation of phenol and phthalic anhydride in the presence of zinc chloride ZnCl2 or concentrated sulfuric acid H2SO4. In the solid state, phenolphthalein molecules are colorless crystals.

Previously, phenolphthalein was actively used in the creation of laxatives, but gradually its use was significantly reduced due to the established cumulative properties.

ADSORPTION INDICATORS

Adsorption indicators are substances in the presence of which a change in the color of the precipitate formed during titration by precipitation occurs. Many acid-base indicators, some dyes and other chemical compounds are capable of changing the color of a precipitate at a certain pH value, which makes them suitable for use as adsorption indicators.

Litmus

This indicator was one of the first reagents used on solid media. Litmus is a complex mixture of natural compounds that is obtained from certain types of lichens. It is used not only as a dye, but also as a means for determining the pH of the environment. This is one of the first indicators that began to be used by humans in chemical practice: it is used in the form of aqueous solutions or strips of filter paper soaked in it. Solid litmus is a dark powder with a faint ammonia odor. When dissolved in clean water, the color of the indicator takes on a violet color, and when acidified it turns red. In an alkaline environment, litmus turns blue, which allows it to be used as a universal indicator for the general determination of environmental indicators.

It is not possible to accurately establish the mechanism and nature of the reaction that occurs when pH changes in the structures of litmus components, since it can contain up to 15 different compounds, some of which may be inseparable active substances, which complicates their individual studies of chemical and physical properties.

How to change the indicator color

Some Android smartphone manufacturers provide users with the ability to change the color of the indicator for various notifications in the device settings. Well, owners of devices that do not provide configuration will have to download a special application for this purpose.

Let's look at where the indication turns on and how to change the color of the notification indicator using the example of Honor and Huawei mobile devices.

To turn on the LED indication:

• Let's go to the device settings.
• Go to the “Applications and Notifications” section.

• Open the “Notifications and status bar” tab and activate the “Indicator flashing” item by moving the toggle switch to the active position.

To set the indicator light for notifications from instant messengers:

• We launch the application and go to its settings, for which we click the three dots on the right at the top of the screen and select the appropriate section.
• Open the item related to notifications and configure the light in notifications from chats and groups. Now, when messages arrive from the application, the indicator will light up in the selected color. If the smartphone does not support this color scheme, the default white will be used.

These steps will have to be repeated for each application from which you want to receive notification signals in the form of a blinking indicator in a certain color.

On certain Xiaomi models, you can also customize the display using standard system tools:

• In the smartphone settings, in the “System and device” block, select the “Advanced” section.
• Click on the “Indicator light” item.
• You can now select the color of the indicator for notifications, messages and calls from the menu.
• Click on each option and select the desired color.

LED indicator settings in different smartphone models may differ or be absent altogether. If the manufacturer did not bother to include them in the menu, software from Google Play will come to the rescue. Let's look at how to change the color of the display using popular utilities available in the official Android application store.

Light Manager

An application for Android devices that allows you to easily configure the operation of the LED indicator, for which you will need to provide the software with the necessary permissions. A request to access notifications will appear the first time you launch the utility. To configure the display using the software, perform the following steps:

• Install Light Manager from Google Play in the standard way.
• We launch the utility and when a request to access your alerts appears, click on the message, then select the Light Manager checkbox.
• We return to the utility interface to configure the reaction of the LED flashlight.
• All settings here are divided into categories, which allows you to change the color and blinking pattern of the light bulb for any of the selected events in the list. Scroll down the list to configure settings for individual notifications. If there is no color next to the application, this means that it is not configured; the configuration is performed by clicking.

The utility allows you to change the LED indicator settings for various events:

• Missed calls, SMS.
• Email notifications.
• Calendar reminders.
• Facebook, Twitter, WhatsApp.
• Low battery level, critical discharge.
• Connecting the charger.
• No signal.
• Enable data transfer and other events.

The application is easy to use; its only drawback is the presence of advertising banners, which can be eliminated by purchasing the Pro version, which costs $1.49.

Light Flow Pro

Another good utility that allows you to change the colors of the LED flashlight for system events and notifications from various applications. The principle of operation of the software is the same as in the case of the software discussed above, but unlike Light Manager, there is the ability to configure sound and vibration.

In the Light Flow Lite version, settings are available only for basic functions, while Light Flow Pro offers customization of up to 600 applications and events with the ability to set a sequence of color notifications. The utility's interface is simple and clear. The main section of the main menu “Notifications” allows you to configure various types of notifications; it contains a list of events in the form of tiles, which can be configured in the application.

To configure the indicator, perform the following steps:

• We install the utility from the Google Play Market, launch it and grant it permissions when requesting access to notifications.
• We select those events to which the LED indicator should react, for which we call up the navigation panel (swipe on the left) and click “Notification Settings”. Click “+” and select event types one by one (special alerts, messages from applications, system services, contacts). When you click on each item, a list of applications, contacts and system services will open - mark those for which we will configure the indicator’s reaction.
• Flagged items are now available in the Notification Settings menu. Go here to set the color, frequency and duration of flickering for selected events. Here you can configure the type of vibrations and sound alerts.

The functionality of Light Flow is impressive, but, according to the software developer, the software solution is not suitable for all smartphone models, so it is better to test the free Lite version first. Much depends on the characteristics of a particular device, that is, when setting up, the number of indicator colors provided by the manufacturer, the possibility of its flickering, the time of continuous operation, etc. play a role.

Universal indicator paper

With the development of science and the advent of indicator papers, the establishment of environmental indicators was greatly simplified, since now there was no need to have ready-made liquid reagents for any field research, which is still successfully used by scientists and criminologists. Thus, solutions were replaced by universal indicator papers, which, due to their wide spectrum of action, almost completely eliminated the need to use any other acid-base indicators.

The composition of impregnated strips may differ from one manufacturer to another, so an approximate list of included substances may be as follows:

• phenolphthalein (0-3.0 and 8.2–11);
• (di)methyl yellow (2.9–4.0);
• methyl orange (3.1–4.4);
• methyl red (4.2–6.2);
• bromothymol blue (6.0–7.8);
• α-naphtholphthalein (7.3–8.7);
• thymol blue (8.0–9.6);
• cresolphthalein (8.2–9.8).

The packaging must contain color scale standards that allow you to determine the pH of the environment from 0 to 12 (about 14) with an accuracy of one whole integer.

Among other things, these compounds can be used together in aqueous and aqueous-alcoholic solutions, which makes the use of such mixtures very convenient. However, some of these substances may be poorly soluble in water, so it is necessary to select a universal organic solvent.

Due to their properties, acid-base indicators have found their use in many fields of science, and their diversity has made it possible to create universal mixtures that are sensitive to a wide range of pH values.

How to setup

To configure the function in question, you will need to contact a specific application. Let's say to change the settings for Whatsapp:

• Log in to messenger.
• Click on the three dots at the top to bring up the menu and select the Settings tab.

• Click on “Alerts” – “Light”.

• Choose the option you like, for example, blue.

How to disable Incognito mode on Honor and Huawei smartphones - instructions
If the smartphone does not support the selected shade, the light will blink white. This way the user will determine which program sent the message without removing the screen lock.

REDOX INDICATORS

Redox indicators

- chemical compounds that change the color of a solution depending on the value of the redox potential. They are used in titrimetric methods of analysis, as well as in biological studies for the colorimetric determination of redox potential.