Category: Chemistry Notes PPT

Properties of Aluminium Sulfate Al₂(SO₄)₃

The chemical formula of Aluminium Sulfate is Al2(SO4)3. It is a chemical compound typically used as a coagulating agent for purification of drinking water, paper manufacturing, and wastewater treatment plants. It is also known as filter alum or dialuminium trisulfate. It is a white crystalline solid in its anhydrous form. However, in its liquid form, it is colourless. Both these forms are non-combustible and non-toxic.

Aluminium Sulfate is water-soluble but insoluble in ethanol. It does not have any odour and has a mildly astringent and sweet taste. When it decomposes it emits highly toxic fumes of Sulphur oxides. Also, the Aluminium Sulfate solution is corrosive to Aluminium. This is produced in the laboratory when Aluminium Hydroxide is added to Sulphuric Acid. Here, we will learn about what is Aluminium Sulfate Al2(SO4)3, the properties of Aluminium Sulfate Al2(SO4)3, its structure and uses.

Aluminium Sulfate Structure Al2(SO4)3 Structure

Now that you have learned what is Aluminium Sulfate, let us take a look at its structure and how it looks. Given below is its structure.

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Aluminium Sulfate Formula

Let us now learn the formula of Aluminium Sulfate and how is this formula derived chemically.

Aluminium Sulfate is known to be an ionic compound, which means that it is a combination of both positive and negative ions. An atom or molecule turns into an ion when it loses or gains electrons. Molecules can be either monatomic, which means that they contain one atom, or polyatomic, which means that they contain more than one atom. Most ionic compounds consist of a one metal atom that is a positive ion, and a radical or negative ion that is a negative ion. 

If you consider Aluminium Sulfate, the positive ion in it is Aluminium ion, Al3+. The radical is the sulfate ion, (SO4)2- that has a negative charge. 

Since all ionic compounds are electrically neutral, there is a ratio of molecular weight by which the aluminum and sulfate ions react, so their electrical charges are cancelled out. You can determine this ratio by the criss-cross method of deriving a chemical formula. Let us see how this method works.

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Here, the sign on the sulfate ion is reversed. Then the charges are put as subscripts on the opposite ion. 

Properties of Aluminium Sulfate Al2(SO4)3

Let us now learn about the properties of Aluminium Sulfate Al2(SO4)3. Take a look at the below table.

Aluminium Sulfate Al2(SO4)3 Uses

Let us now learn about the common uses of Aluminium Sulfate.

1. Aluminium Sulfate is used in the purification of water.

2. It is used to prepare baking soda.

3. It is used for dyeing clothes.

4. It is used for gardening purposes and helps to balance the soil pH.

5. Aluminium Sulfate is used in making paper.

6. It is also used for making different prints on cloth.

7. It is used in concrete as a waterproofing agent and an accelerator.

8. It is used in making the firefighting foam.

9. It is also used in the treatment of sewage in water treatment plants.

10. Aluminium Sulfate is used as a fireproofing agent.

In this article, we will discuss Ammonium hydroxide, its formula and structure use and properties. Do not forget to refer to the frequently asked questions at the end for clearing your doubts if you incur any while going through the topic.

Ammonia Hydroxide is a colourless liquid that comes under a class of substance known as costex. When Ammonia dissolves in water it results in the formation of ammonia hydroxide.

Ammonium hydroxide is a solution where ammonia is mixed in water. It is denoted by the symbols NH3(aq). The ammonium hydroxide is an alkali with a composition of [NH₄⁺]OH^– ions; it is not possible to isolate samples of NH₄OH.

 

Except in highly dilute solutions, the ions NH₄⁺ and OH^– do not account for a significant fraction of the total volume of ammonia.

 

The chemical is also known by many other names like:

• Ammonia water

• Ammoniacal liquor

• Ammonia liquor

• Aqua ammonia

• Aqueous ammonia

• Dilute ammonia

It is also known simply as Ammonia.

Chemical Formula for Ammonium Hydroxide: NH4OH or H5NO

 

IUPAC Name: Ammonium hydroxide

 

Synonyms: 

• Ammonium hydroxide

• Ammonia, aqueous solution

• Ammonium hydroxide solution

• Ammonia water

• Ammonia, monohydrate

Appearance: It appears as a colorless liquid

 

Structure

The compound structure is formed by one hydroxide anion (OH–) and one ammonium cation NH4+ which share an ionic bond. In the common representation used for organic molecules, its chemical structure can be written as below.

 

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Preparation of Ammonium Hydroxide

NH3 + H2O → NH4OH

 

The Ammonium hydroxide is prepared by saturating water with gaseous ammonia.

 

Properties

Physical Properties of Ammonium Hydroxide:

• Solubility – Miscible in water

• Specific gravity – It is typically 0.9 and actually depends on the strength of the solution.

• Melting Point – -57.5°C (25%).

• Boiling point – 38°C and 100°C based on the concentration

• Auto- Ignition temperature – 651°C.

• Molar Mass – molecular weight is 35.05 g/mol.

• Density – 0.91 g/cm³ (25%)

• Vapour pressure – Its v.p is 115 mm at 20°C

Chemical Properties:

Basicity of ammonia in water

 

Ammonium hydroxide is a weak basic compound that does not dissociate completely in water leaving the next equilibrium with ammonium ion and hydroxide ion

 

NH4OH + H2O ⇌ NH4+ + OH−

 

The equilibrium is used to control the pH in solutions because the ion OH^– raises a solution’s pOH or basicity level.

 

Saturated Solutions

Ammonia’s solubility is decreased in solvent liquids as the temperature increases in the solvent increases. 

 

Ammonia solutions decrease in density as the dissolved ammonia concentration increases. At 15.6 ° C (60.1 ° F), a saturated solution has a density of 0.88 g / ml and contains 35.6 percent ammonia by mass, 308 grams of ammonia per liter of solution, and molarity of about 18 mol / L.

 

The molarity of the saturated solution decreases at higher temperatures, and the density increases. The ammonia gas is released upon heating of saturated solutions.

 

Ammonium Hydroxide Uses

• Diluted ammonia (1–3 percent) is also a component of many cleaning agents, including many formulations for window cleaning.

• Aqueous ammonia may be used in industry as a precursor to certain alkyl amines, whereas anhydrous ammonia is usually preferred.

• The vapor absorption process became popular and widely used using the water-ammonia systems.

• Ammonia is used to make monochloramine, used as a disinfectant.

• Aquarians use ammonia to establish a new fish tank using ammonia, called fishless cycling. 

• Ammonia solution is used to treat straw and to produce “ammonia straw” which makes it more edible for cattle.

• Also used in the production of soaps, ceramics, detergents, inks and explosives, and pharmaceuticals.

• It is also used as an additive for maintaining a proper level of acidity in food.

• Ammonium hydroxide is also used as a refrigerant.

• Used in the manufacturing of rayon and other Textiles as well.

• Used as a purpose cleaner for surfaces like porcelain, glass, ovens, and stainless steel.

• It is also an effective antimicrobial agent due to its pH abilities.

• It is often used as a base in inorganic analysis and also as a complexant.

NH4OH Hazards

Health Hazards:

Inhalation, ingestion, or contact with material from the skin can cause serious injury or death. Contact with the molten material can cause severe skin and eye burns. Remove any touch to the skin. Touch or inhalation results may be adjourned. Fire can create gases that are irritating, corrosive, and/or toxic. Runoff from fire or dilution water can be corrosive and/or toxic, leading to pollution.

 

Fire Hazards:

Non-combustible, material does not burn itself but can decompose to create corrosive and/or toxic fumes when heated. Some are oxidizing agents and may ignite fuels (wood, paper, gasoline, clothes, etc). Metal contact can result in the formation of flammable hydrogen gas. Containers can explode when dry.

 

Conclusion

This is all about ammonium hydroxide, its physical and chemical properties. Focus on its features and how it is used in different aspects. Learn how it can be hazardous to our health. Understand why it is basic from its structural features. 

Animal fibres are naturally occurring fibres that are sourced from animals, as the name suggests. Animal fibres are made up of different types of proteins in general. Some of the most common animal fibres are wool and silk. You must know that all animal fibres are extracted from different animals and hence have different properties from one another. Also, the kind of fibres depends from one animal to another. 

Consider, for example, both Merino and Cotswold are two different kinds of wool that are extracted from different species of sheep. Merino is known for its softer texture, whereas Cotswold is known for its coarse texture. You must also know that the natural fibres from animals tend to vary in consistency than the synthetic fibres. The synthetic ones are more uniform. We will learn today about what animal fibres are, the difference between animal fibres and plant fibres, and the different types of animal fibres.

Names of Animal Fibres

The fibres obtained from animals are generally textile. These fibres are generally produced from the animal’s fur, skin, hair, or even secretion in the case of the silkworm. Once these animal fibres are extracted they are generally knitted or woven for forming beautiful animal fabrics. If you have to name two fibres obtained from animals, they can be silk and wool. 

However, if you consider historically, these animal fibres have been employed for manufacturing warm and soft jackets, shawls, blazers, coats, ponchos, and several other forms of clothes and accessories. If you have to name any two animal fibres applications that are rougher, they are usually covers, carpets and rugs.

Difference Between Animal Fibres and Plant Fibres

Types of Animal Fibres

If we have to name two animal fibres that are widely used, they are wool and silk. Let us now learn about the types of animal fibres in detail.

1. Wool

Wool is an animal fibre derived from different animal furs which belong to the Caprinae family. We usually relate wool to sheep, however, wool can also be derived from other animals like goats, rabbits, and alpacas. Different kinds of wool from different animals have different properties from one another. The main difference between the wool and hair of sheep is that the wool of the sheep consists of scales which overlap in the same manner as the shingles on a roof. Many kinds of wools are also known to possess more than 20 kinds of such bends in just one inch. However, the diameter of one strand of the wool ranges from 17micrometres to about 35 micrometres.

Let us discuss about the feature of those different types of wool fibres – 

1. Angora wool, the rabbit hairs obtained from a special species of rabbits named as Angora rabbit. The fur of the angora rabbits are considered to be extremely soft and pleasant to touch, thus due to its desirable characteristics are in a very high demand. It is often mixed with other types of wool to add warmth and softness in the final product.

2. Alpaca fibre: this is obtained from one of the South American camelid mammal species, by the same name Alpaca. This wool is very light in comparison to the normal sheep fibre and not only that, it is warmer than the traditional sheep wool.

3. Wool obtained from the american bison, known as the bison wool, is also quite famous in the textile industry. 

4. One extremely famous type of wool goes by the name of Cashmere wool (derived from the word Kashmiri), and is processed from the fur of the Cashmere goat found in the Kashmir territory of India. This type of wool has a luxurious texture in it and is extremely soft and lightweight. Kashmir shawl (also spelled as Cashmere) created from the Cashmere wool is quite popular in the textile industries around the world.

5. Like rabbits, goats also have pieces with the name of angora goats, the fur of which is called the Mohair wool, this type of wool is considered very similar to silk. Mohair is famously known for its durability.

2. Silk

Silk is regarded as a naturally occurring protein fibre. It can also be woven into textiles in different ways. The most commonly known silk form is the which is obtained from the larvae of Bombyx mori species. Silk rearing is called sericulture. The degummed fibres which are obtained from Bombyx mori have a diameter which ranges from 5 – 10 m. There are different types of silk which are famous for their shiny appearance. This is because of the triangular prism-like and cross-sectional structure of these fibres. These prism-like fibrous structures tend to allow light which is incident to the silk fibres to refract at varying angles.

You must know that one whole silkworm cocoon produces one long fibre. Therefore, one should be careful while unwinding these fibres from the silkworm cocoons. Also, the quality of the silk fibres depends on how healthy the silkworm is. This, in turn, depends on the living conditions and the food which they are provided with.

Spider silk is amongst the most powerful naturally occurring fibres known to man. It is the strongest dragline silk which is believed to be about three times stronger than kevlar and more than five times tougher than steel. There are some types of spider silks that are known for their enhanced elasticity. The silk which is woven by the ogre-faced spider is considered to be stretchable more than five times its length without damaging itself!

Electrophoresis is known as the movement of the dispersed or colloidal particles that are suspended in a given fluid because of their interactions with the electric field that is uniform partially. The electrophoresis process of the positively charged particles called cations is often referred to as cataphoresis. On the other hand, the electrophoresis of the negatively charged particles called anions is referred to as anaphoresis. It is caused due to the presence of an interface that is charged and lies between the surface of the particle and the surrounding fluid. It makes for the basis for different analytical techniques that are used in Chemistry to separate the molecules according to their charges, size, or binding affinity.

 

The electrophoresis process is also used in laboratories for separating the macromolecules depending on their size. This technique includes the application of a negative charge so that the proteins would move towards the positive charge. Electrophoresis is also widely used in the analysis of DNA, RNA and different proteins. We will discuss the electrophoresis uses and the application of electrophoresis in chemistry in this article.

 

 

Application of Electrophoresis in DNA Analysis and DNA Fragmentation

Amongst the most important applications of the process of electrophoresis is in the analysis of DNA analysis the studying of DNA fragments. DNA is known for the negative charge consistency that it holds and it is affected due to the presence of the electrical current. When pressure is exerted on it by the electric field, DNA starts to break down into small and large fragments. This happens because different kinds of DNA fragments get affected by the current on different scales. A test medium like an agarose gel or an acrylamide gel is used for freezing the separated fragments of a particular DNA strand. The electric field is then removed and the study of these fragments is carried out.

 

Application of Electrophoresis in Protein Detection

A type of electrophoresis known as immunoelectrophoresis is common and used for analysing several kinds of proteins’ existence and how they behave chemically in different environments. When irregular molecules of proteins are formed they get triggered because of various medical conditions like multiple sclerosis, kidney failures and even different kinds of cancers. The irregular proteins are detected by the method of electrophoresis on the urine or blood samples and frequently checking its results for any kind of deviations from standard forms and amounts of the protein. Immunoelectrophoresis is also used for the detection of specific proteins which are called immunoglobulins.

 

Application of Electrophoresis for Testing Antibodies

Electrophoresis plays a variety of essential functions when it comes to the testing of antibiotics.

 

The most common applications of the process of electrophoresis in this field are the testing of antibiotics to check their purity. Electrophoresis is used in a solution that consists of the antibiotic to be tested in the form of a paper strip. This strip is impregnated with a capillary or the antibiotic which is filled with the drug.

 

Electrophoresis is also used for determining the strength of the antibiotic having a vital importance in regards to administering the exact dosages. Also, the antibiotic research field has a common ground along with the genetic testing field. Hence, electrophoresis also helps in discovering the genes which tend to indicate the resistance to a specific kind of antibiotics.

Factors affecting Electrophoresis

Below are the factors that affect the process of electrophoresis. 

1. Electric Field

The electric field is one of the major factors affecting the process of electrophoresis. The movement of ions in electrophoresis depends on the current, resistance, and voltage in the electric field.

During electrophoresis, the voltage of the electric field affects the travel time of the molecules being separated. With higher voltage, the DNA will be able to travel through the gel much faster. However, excessively high voltages can melt the gel or even cause distortion of DNA bands. 

The distance travelled by the ions in electrophoresis is directly proportional to the time and current. Since the current is conducted between electrodes, the increase in voltage leads to an increase in the number of charges towards each electrode. 

Resistance of electrophoresis depends on the thickness of the gel, size, buffer conductivity, temperature, and the amount of buffer. It usually decreases with an increase in the temperature. The amount of resistance will determine whether the circuit is a bad conductor or a good one. 

2. Sample 

The size, shape, and charge of the sample, which is being separated during electrophoresis, affect its migration rate. With an increase in the charge, the rate of migration will also increase. Moreover, the rate of migration is also affected by the change in the size of the molecule and the shape of the sample. It is inversely proportional to the size and shape of the sample. 

3. Buffer 

The migration rate of the compound is affected by the buffer, which stabilises the pH levels of the supporting medium. Some of the most commonly used buffers for the electrophoresis process are EDTA, formate, Tris, citrate, barbitone acetate, and pyridine. The migration of the sample used can be affected if the buffer binds to the molecules, which is why it should never bind to them. 

The proportion of the current carried by this buffer will increase while the current carried by the sample being separated will decrease. At low ionic strength, the proportion of the current carried by the buffer will decrease and the one carried by the sample will increase. 

Heat generation is oftentimes a problem that occurs during electrophoresis. The heat generated during electrophoresis changes the density and viscosity of the electrophoretic media. It can also damage the equipment by melting the plastics, cracking the glass plates, warping, etc. 

In case the conductivity of the supporting medium is high, the process of electrophoresis becomes more difficult. It is because solutions with high conductivity lead to a lower field strength per current and the heat load on the system increases. 

4. Supporting Medium

The supporting medium used in electrophoresis can affect the migration rate of the sample. Usually, the inert medium is preferred during the process of electrophoresis. This medium, however, can cause molecular sieving, absorption, or electro-osmosis that can affect electrophoresis. Absorption can cause tailing of the sample, which causes a disruption in the movement of the sample. It also reduces the rate and resolution of the separation during electrophoresis.

The Arrhenius equation is used for calculating the rate of reaction. It is a crucial part in chemical kinetics. It helps to understand the impact of temperature on the rate of reaction. This equation was first introduced by Svente Arrhenius in 1889.

In the equation, A = Frequency factor

K = Rate constant

R = Gas constant

Ea = Activation energy

T = Kelvin temperature

The collision theory is the foundation for the Arrhenius equation. As per this theory, the reaction is essentially a collision involving two molecules ( of same or different substances) to form the intermediate. This intermediate that is formed is unstable, and itt exists for a short duration of time. The intermediate breaks down thereby giving out two molecules of product. The energy that is used for forming this intermediate is called the activation energy.

If we look at log on both sides of the equation, the equation becomes

Ln is the natural algorithm, and these values can be picked up from a logarithmic table.

For the graphical representation, 

When we compare this equation with the straight-line equation, we get

X = [frac  {1} {T}]

Y = ln k

M = [frac  {-Ea} {R}]

C = ln A

This provides the straight-line graph but has a negative slope. 

Plotting the k v/s [(frac  {1} {T})].

Impact of Temperature

With the help of the graph, we can conclude that the rate of reactions and temperature are proportional. As temperature increases, the rate of reaction also tends to increase. There is an increase in kinetic energy with temperature. So when the temperature is increased, the number of molecules having kinetic energy higher than activation energy also increases. This leads to a rise in the rate of overall reaction as the activation energy decreases. 

For the 10K shift in temperature, the rate is almost doubled. 

Let us consider the Arrhenius equation at times T1 and T2 where the rates of reaction are denoted by K1 and K2 respectively. 

In K1 = [frac  {-Ea} {RT_1}] + In A —— (1) 

In K2 = [frac  {-Ea} {RT_2}] + In A —— (2)

Now we subtract 1 from 2

In K2 – In K1 equals to [frac  {Ea} {RT_1}] – [frac  {Ea} {RT_2}]

In [frac  {K_2} {K_1}] = [(frac  {Ea} {R})] [frac  {1} {T_1}] – [frac  {1} {T_2}]

Converting to log, 

Log [(frac  {Ea} {2.303R})] [frac  {T_2-T_1} {T_1T_2}]

 

The Arrhenius equation also suggests that uncatalyzed reaction is more impacted by temperature in comparison to the catalyzed reaction. 

Real-Life Examples of This Theory:

• Milk gets sour faster when it is kept at room temperature instead of being kept in the refrigerator.

• Eggs tend to hard boil faster when they are at sea level in comparison to mountains or elevated levels.

• The butter tends to become rancid at a faster rate in summer than it does in winter

• Cold-blooded animals or species like reptiles and insects become more lethargic during colder days. 
  

Significance of Arrhenius Equation

• This equation enables the accounting of factors that have an effect on the rate of reaction and which is not possible to be determined by the rate law.

• It helps in finding the impact of energy barrier, frequency, temperature, the orientation of collisions, and presence of catalyst using the equation. 

In this article, we will learn about the following things: the atomic mass of elements in detail, what is the atomic mass of all elements, and what is the atomic number and atomic mass of elements.

The atomic mass of a solitary atom is its absolute mass and is regularly expressed in atomic mass units or amu. For example, a normal carbon atom with six neutrons and six protons is denoted as carbon-12. It has an atomic mass equal to 12 amu. The atomic mass number is usually rounded off to the nearest whole number.

Since an element’s isotopes have distinctive atomic masses, researchers may likewise decide the general atomic mass—once in a while called the atomic weight—for an element. The general atomic mass is the normal of the atomic masses of the apparent multitude of various isotopes in an example. Every isotope’s contribution to the normal is controlled by how huge a fraction of the example it makes up. The overall atomic masses that are given in periodic tables like the one for hydrogen are determined for the naturally occurring isotopes of each element, weighted by the weight of those particular isotopes on earth.

The Periodic Table

In 1869, when Dimitri Mendeleev put together the first periodic table, the elements in the table were arranged in the order of increasing atomic mass. This approach is because the nucleus of the atom was yet to be discovered, and the chemists at the time had no understanding of the internal structure of atoms. Until the discovery of the structure of the atom, it was not known that the properties of the elements were governed by the atomic number.

Atomic Number

The atomic number gives a number of how many protons are inside the nucleus of the atom. Elements are identified based on the number of protons in the nucleus regardless of the number of neutrons present. Neutrons are uncharged subatomic particles which are stable when bound in an atomic nucleus. Atoms of all elements have neutrons in the nucleus except hydrogen.

The atomic number is important because the number of protons determines the number of electrons that surround the nucleus. The number of electrons in an element considerably determines the chemical behavior of the element. 

When observing the periodic table, one can see that elements are arranged on the basis of increasing atomic numbers. Elements that have similar qualities fall into the same column or group. For example, the elements in Group 1A are mostly soft metals that are highly reactive with water. Similarly, the elements in Group 8A are unreactive gaseous at room temperature. In the same group, a periodic repetition of properties can be seen in the elements with increasing mass.

Atomic Number of Elements from 1 to 30

Let us take a look at what is the atomic mass of elements from 1 to 30. Given below is the atomic mass of elements list.

This was the atomic mass of the first 30 elements. Let us now learn the difference between atomic number and atomic mass of elements.

Isotopes

Before going into atomic mass, it is essential to learn about isotopes. Atoms of the same element that have a different number of neutrons are called isotopes. The isotope of a given element is defined by adding the number of protons and neutrons in its nucleus. An element (which has the same atomic number) can have multiple isotopes with different numbers of neutrons. The most common examples are the isotopes of carbon, 12C, and 13C which possess 6 and 7 neutrons, respectively. Isotopes vary in their abundance in nature depending on the source of the materials.

Atomic Mass

The atomic mass is the average mass of the atoms of an element measured in the atomic mass unit (amu) or Daltons, D. The atomic mass is determined by averaging the weight of all the isotopes of the element. The averaging procedure also involves taking into consideration the abundance of each isotope and multiplying it with the mass of each. 

Consider the gas neon, which has three isotopes: 

1. neon-20: It is made up of ten protons and ten neutrons. The atomic mass unit of the gas is 19.992, and the abundance of the gas is 90.48%. 

2. neon-21: It is made up of ten protons and eleven neutrons. The atomic mass unit of the gas is 20.994, and the abundance of the gas is 0.27%. 

3. neon-22: It is made up of ten protons and twelve neutrons. The atomic mass unit of the gas is 21.991, and the abundance of the gas is 9.25%. 

To determine the atomic mass of neon, the average of the isotopes need to be extracted: 

0.9048 × 19.992 = 18.09 amu

0.0027 × 20.994 = 0.057 amu

0.0925 × 21.991 = 2.03 amu 

The average atomic mass is thus: 20.18 amu

The atomic mass of elements directly relates to the concept of “mole” which is an important way of measuring the amount of substance. The relation between the atomic mass and the number of moles is that, when measured, the amu directly gives a measure in grams of the element present in one mole. 

For example, iron has an atomic mass of 55.847 amu. Therefore, one mole of iron has a weight of 55.847 grams. The same concept is also used to determine the molar quantities of ionic molecules and compounds. For example, one mole of sodium chloride (NaCl) has a molecular mass of 58.44 amu (Na: 22.989 amu Cl: 35.453 amu) which gives the molar weight of salt as 58.44 grams. Similarly, the molecular mass of water is 18.02 amu which gives a molar mass of 18.02 grams.

Difference Between the Atomic Number and the Atomic Mass of Elements

Let us now learn about the difference between the atomic number of elements and their atomic mass.