The Level or Degree of Acidity of a Solution
To express the level or degree of acidity of a solution, in 1910, a Danish expert, Soren Lautiz Sorensen introduced a simple number. This number is obtained from the logarithm of the H + concentration.
This number is known as the pH scale. PH prices range from 1 - 14 and are written:
The concept of pH
From the description above we can conclude that:
The solution is neutral if [H +] = [OH–] or pH = pOH = 7.
b. Solution is acidic if [H +]> [OH–] or pH <7.
c. Solution is basic if [H +] <[OH–] or pH> 7.
Weak base
The stronger the base, the base equilibrium reaction is leaning to the right, as a result, the Kb increases.
Therefore, the price of Kb is a measure of base strength, the greater the Kb the stronger the base.
Based on the above equation, because on a weak base [M +] = [OH–], the above equation can be changed to:
Weak Acid 1
Base example
Degree of Acidity (pH)
The concept of pH
Because the pH and concentration of H + ions are associated with negative signs, the greater the concentration of H + ions the smaller the pH, and because the logarithmic base number is 10, the solution with a different pH value of n has a H + ion difference of 10n.
Notice the example below.
If the concentration of H + ions = 0.01 M, then the pH = -log 0.01 = 2
If the concentration of H + ions = 0.001 M (10 times smaller) then the pH = - log 0.001 = 3 (up 1 unit)
So it can be concluded:
The greater the concentration of H + ions the smaller the pH
Solutions with pH = 1 are 10 times more acidic than solutions with pH = 2.
PH measurement
To determine the pH of a solution can be done in several ways, including the following.
Using Multiple Indicators
Indicators are weak organic acids or weak organic bases that can change color at a certain pH price range (James E. Brady, 1990).
The pH value of a solution can be estimated using a pH indicator route.
The indicator has different color change routes.
Thus, from a solution test with several indicators, the pH slice area will be obtained.
For example, a solution with blue thymol bromine (6.0 to 7.6) is blue and with phenolphthalein (8.3-10.0) is colorless, the pH of the solution is 7.6–8.3.
This is because if the blue thromol bromine is blue, it means that the pH of the solution is greater than 7.6 and if the phenolphthalein is colorless, the pH of the solution is less than 8.3.
Also Read Articles That May Be Associated: Compounds: Understanding, Characteristics, Traits, And Kinds With Examples In Complete
Characteristics and Properties of Acid, Base and Salt
Acid characteristics
The word acid (acid) comes from the Latin acidus which means it has a sour taste. One definition of acid is a substance which, if dissolved in water, will produce hydrogen ions (H +). In general, acids have the following characteristics:
Sour taste when tasted (don't test strong acids by tasting)
Acidity less than 7 (pH <7)
It stings when touched, especially strong acids
Reactions with metals are corrosive (cause rust, can also damage skin tissue / irritation and pierce objects made of wood or paper if the concentration is high)
An electrolyte solution that can conduct electricity.
Acid Properties
Have a sour taste
Change blue litmus to red
Are corrosive, can dissolve various metals
Can dissolve limestone to produce carbon dioxide gas.
Acid rain
Rainwater whose pH is less than 5.6 is called acid rain.
Acid rain occurs because the air is polluted by acidic oxides, especially sulfur oxides (SO2) and (SO3), nitrogen oxides (NO2) sulfur oxides from fossil combustion, and nitrogen oxides from motor vehicle fumes and industrial fumes.
Losses that can be caused by acid rain are:
Damaging plants, because acid rain can change the pH of the soil.
Reducing soil fertility, because acid rain can flush nutrient elements in the soil.
Turn off aquatic biota, because acid rainwater can change the pH of the water
Damaging buildings, especially those made of metal and marble.
Characteristics of Bases
Basa (alkali) comes from Arabic which means ash. One definition of a base is a substance which, if dissolved in water, will produce hydroxide ions (OH-). Generally bases have the following characteristics:
Bitter taste when tasted
In its pure state it is generally in the form of solid crystals
Acidity is greater than 7 (pH> 7)
Feels slippery on the skin (don't test strong bases by touching them)
Has the caustic nature of damaging the skin if the base content is high
Can emulsify oil
Is an electrolyte, the solution can conduct electricity
Basic Nature
Some basic properties are as follows:
Bitter taste
Change red litmus to blue
React with fat to form soap.
Neutralize acidic properties
Are corrosive, especially strong bases.
Bases in everyday life
Fire soda (sodium hydroxide, NaOh), functions to:
- Dissolve fats and oils
- clean the oven
- destroy seloluse
Calcium hydroxide or lime (Ca (OH)
Ammonia (NH3 solution) is used as a glass cleaner.
Indicator
The way to find out whether a substance is classified as acidic or basic is to use an indicator.
Indicator is a substance that can be paid for colors when inserted into acidic or basic compounds. Indicator can be paper or solution, indicator in the form of paper is litmus paper.
There are two kinds of litmus paper, namely red litmus and blue litmus. How to use is litmus paper inserted into the compound, then see the color change.