Tag: Equilibrium

An Introduction to Acids and Bases

Acids are substances with a pH below 7 that release hydrogen ions or a proton when combined in an aqueous solution. The dissociable protons or hydrogen groups, also known as acidic hydrogen, that easily split apart in solution or the presence of bases are the main constituent of these acids.

Bases are substances that yield hydroxyl ions when combined with water in an aqueous solution when combined with water in an aqueous solution, yield hydroxyl ions. Their pH is higher than 7. Therefore, a base has a basic group that separates in an aqueous media or a dissociable hydroxyl group. Bases may also be referred to as substances that are hydrogen acceptors because they are substances that can either receive or accept hydrogen ions.

The pH Scale

The pH scale determines the strength of an acid or base by specifying the degree of dissociation. A strong acid or base dissociates in water, producing massive amounts of hydrogen or hydroxyl ions. A dissociation constant is used to calculate an acid or base’s dissociation of an acid or base.

Strong Acid

Since extremely acidic hydrogens are extremely acidic hydrogens present, strong acids HA has a high dissociation. Commonly, these hydrogens are attached to extremely electronegative groups (often halogens like chlorine, fluorine, and iodine). 

Low pH is found in strong acids. The amount of hydrogen ions in a solution is related to the pH. The negative logarithm of the concentration of hydrogen ions is the mathematical representation of pH.

\[pH =  – \log [{H^ + }]\]

The dissociation constant of acids, a parameter \({K_a}\), is used to account for the degree of dissociation. Increased dissociation and hence higher acidity are indicated by a high \({K_a}\) value. 

In chemistry, the \(p{K_a}\) value—the negative logarithm of \({K_a}\)—which is the logarithmic acid dissociation constant—is taken into account for convenience. Therefore, stronger acids will have a low pKa value and a high acid dissociation constant \({K_a}\) value, and vice versa.

\[p{K_a} =  – \log {K_a}\]

 Examples of Strong Acids

Strong Acids	Formula
Hydrochloric Acid	HCl
Sulphuric Acid	H2SO4
Nitric Acid	HNO3

Strong Base

Strong bases NaOH are substances that split apart in solution to form high quantities of hydroxyl ions. In addition, bases have the potential to be strong proton acceptors, which means that they could grab a proton from the water molecule \({H_2}O\) in an aqueous solution to produce an \(O{H^ – }\) ion.

\[NaOH \to N{a^ + }(aq) + O{H^ – }(aq)\]

The base dissociation constant Kb describes the level of dissociation in the case of bases. Stronger bases are associated with lower values of the logarithmic base dissociation constant, or, which is equivalent to \(p{K_a}\).

\[p{K_b} =  – \log {K_b}\]

Similar to pH, the concentration of hydroxyl ions is related to pOH. A strong base that supplied a lot of hydroxyl ions would have low pOH because the concentration of hydroxyl ions is a negative logarithm.

\[pOH =  – \log [O{H^ – }]\]

The equation pH + pOH = 14 relates pH and pOH in an aqueous solution. If one is known, the other can be used to compute either pH or pOH.

Strong bases commonly have a pH range of 13–14.

Examples of Strong Bases

Strong Bases	Formula
Calcium Hydroxide	Ca(OH)2
Sodium Hydroxide	NaOH
Potassium Hydroxide	KOH
Lithium Hydroxide	LiOH

Summary

Strong acids and bases are the subjects of this article, which also examines how strong acids or basic solutions are based on their pH. Strong acids and strong bases have a high degree of dissociation. Strong acids and bases dissociate in solution, releasing a lot of proton and hydroxyl ions. Strong bases have high pH, whereas strong acids have low pH. 

Frequently Asked Questions

1. What is the Body’s pH?

Ans. The pH of human blood ranges from 7.35 to 7.45, making it very slightly alkaline. With a pH range of 1.5 to 3.5, the human stomach is the most acidic organ in the body. To break down food for digestion and remove any unwanted microorganisms, the stomach is kept at a low pH.

2. What are the Main Differences between a Strong Acid and a Weak Acid?

Strong Acids	Weak Acids
When exposed to water, strong acids completely dissociate into their ions.	In an aqueous solution, weak acids are molecules that partially dissociate into ions.
A strong acid solution has a very low pH.	A weak acid solution has a pH of 3-5.
It releases all the H+ ions to the solution.	Partially releases all H+ ions to enter the solution.

3. What are the Main Differences between a Strong Base and a Weak Base?

Strong Bases	Weak Bases
In a solution, a strong base can completely dissociate into its cation and hydroxyl ion.	A weak base partially dissociates into its hydroxyl ion and cation, resulting in an equilibrium state.

Introduction

Pressure can be defined as the force exerted perpendicularly per square unit of area of any object. It is represented by the formula,                                                                                                                        

                                                             P = F ⁄ A

where P is the pressure, F is the force exerted on the object, and A is the area of the object. Pressure is measured in pascal, and is classified into absolute, atmospheric, differential, and gauge pressure. A change in pressure has different effects on different states of matter.

Change in Pressure

Since the pressure exerted on an object is the amount of force applied per unit area of that object, a change in area or a change in the amount of exerted force can result in a change in pressure. For example, if the surface area decreases, the pressure increases simultaneously when the surface area decreases, the pressure decreases provided that the force applied remains constant. 

Effect of Pressure on the States of Matter

Pressure change can have different effects on different states of matter. By exerting pressure on the matter particles, we can draw them closer. Therefore, applying pressure can cause liquids to turn into solids, and when pressure is applied to a gas that is contained in a cylinder, the gas begins to compress and turn into a liquid. As pressure rises, the volume of the gas reduces, which causes the gas to change into a liquid and then finally a solid. The volume of a gas is inversely related to its pressure and directly relates to the number of molecules it contains.

Pressure has less of an impact on solids because they are non-compressible forms of matter. By applying pressure and lowering the temperature, liquids can be transformed into solids.

Effect of Pressure on Equilibrium

The equilibrium will adjust to minimize a change in the pressure of a gaseous reaction mixture. If the pressure is raised, the equilibrium will change to favour a fall in the pressure. The equilibrium will change if the pressure is reduced to favour an increase.

When a system’s volume is reduced, the pressure will rise (and the temperature is constant). A greater number of collisions occur with the container’s walls. There will be fewer collisions and hence less pressure if there are fewer gas molecules. The equilibrium will change in a way that reduces the number of gas molecules, which will likewise reduce the pressure. To forecast which way equilibrium will shift in response to a change in pressure, we must consider how many gas molecules are involved in the balanced reactions.

For example, the chemical reaction between nitrogen and hydrogen is shown below:

                                                           N2 (g) + 3H2 (g)→ 2NH3↑

The proportion in the equation that balances is 1:3:2. In other words, the 1N2 molecule combines with the 3H2 molecule to produce NH3 gas (from the balanced equation). Four molecules of reactant gas must therefore be present to produce two molecules of product gas.

• Pressure buildup will favour the reaction which results in fewer gas molecules. Because there are fewer product gas’ molecules, the forward reaction is more advantageous. Due to the rightward shift in equilibrium, the yield of NH3 will rise.
• The reaction that produces more gas molecules will be more favourable as pressure drops. If there are more reactant gas molecules present, the reverse reaction is more favourable. As a result of the equilibrium shifting to the left, the yield of NH3 will decline.

Some Facts

• Pressure is directly proportional to the temperature.
• In contrast to solids and liquids, gases are more easily subjected to pressure.
• Compared to gases, solids and liquids are less sensitive to pressure.
• When air pressure is raised, the boiling point of water rises.
• The equilibrium will adjust to minimize the change in pressure of the gaseous mixture.

Frequently Asked Questions

1. Does Changing the Size of the Container Affect the Pressure?

Ans: No change in concentration could change the pressure if the equilibrium reaction does not involve a change in the number of molecules in the gas phase. Therefore, altering the container’s size without also altering the pressure would have no impact on the reaction. The number of molecules stays constant and applies the same pressure whether the container size decreases or grows.

2. How can the Physical Condition of the Matter be Altered?

Ans: It is also possible to change the physical state of matter by adjusting the pressure that is applied. For example, by applying pressure and lowering the temperature, gases can liquefy. 

3. How does Pressure Affect the Boiling Point of a Liquid?

Ans: All liquids evaporate with an expansion. The expansion and delay of vaporization are the results of pressure on the surface. As a result, when pressure is applied, the boiling point rises.