Quantitative estimation is a branch of analytical chemistry which helps to determine the quantity of a substance present in a given sample. One of the important methods in Quantitative estimation is the Volumetric analysis, also called titration. It is used to determine the unknown concentration of a sample by measuring its volume. In a titration, a solution of unknown concentration is reacted with a solution of known concentration. The solution taken in the burette is called the titrant and the solution taken in the conical flask is called the analyte. This video explains how to determine the strength of…
Potash alum is a double salt of potassium sulphate and aluminum sulphate. It is highly water soluble. To prepare pure crystals of potash alum, dissolve the sample in distilled water and remove the insoluble impurities by filtration. This solution is concentrated to the crystallization point and cooled. Colourless transparent crystals of potash alum separate. The soluble impurities are left behind in the mother liquor. Potash alum has an octahedral geometry. This video explains how to prepare pure crystals of potash alum form an impure sample through crystallization.
All matter can be classified into two categories: pure substances and mixtures. A pure substance consists of elements or compounds.Elements are the simplest substances in nature and a compound is formed when two or more elements chemically combined together. The components of a compound lose their individual properties and the properties of a compound are different from their individual components. A mixture is a combination of two or more substances which are not chemically the same. In a mixture, the components are present in any proportion and they can be identified visually within the mixture. The properties of a mixture…
Manganese is a chemical element with symbol Mn and atomic number 25. It is not found as a free element in nature; it is often found in minerals in combination with iron. The most common oxidation states of manganese are +2, +3, +4, +6, and +7, though all oxidation states from −3 to +7 have been observed. The most stable oxidation state for manganese is +2, which has a pale pink color, and many manganese(II) compounds are known, such as manganese (II) sulfate and manganese (II) chloride. This video explains how to test for the presence of manganese (II)…
The kingdom Plantae consists of different types of plants that are eukaryotic, multicellular organisms having photosynthetic pigments and cell walls. Plants are classified in several different ways based on various external and internal characteristics. Based on these characteristics, plants are classified into multicellular groups such as thalophytes, bryophytes, pteridophytes, gymnosperms and angiosperms. This video describes the characteristics of spirogyra, agaricus, moss, fern, pinus and an angiosperm.
Transpiration is a process that involves loss of water vapour through the stomata of plants. There is a close inter-relationship between transpiration and leaf structure. The rate at which transpiration occurs refers to the amount of water lost by plants over a given time period. Plants regulate the rate of transpiration by opening and closing of stomata. Each stomata has a slit like opening called the stomatal pore, which is surrounded by two special cells called the guard cells. These special cells help to regulate the rate of transpiration by opening and closing the stomata A number of external factors…
The mass (m) of an object is a fundamental property of the object. In everyday usage, mass is often referred to as weight. An object’s weight depends on its environment, while its mass does not. In science, the weight of an object is the force on the object due to gravity. The force acting on an object perpendicular to the surface is called thrust. The effect of thrust depends on the area on which it acts. The thrust on unit area is called pressure. This video explains how to study and compare the pressure exerted by a solid iron…
Phosphates are inorganic salts containing phosphate ion. The It contains a central phosphorous atom surrounded by four oxygen atoms in a tetrahedral arrangement. The most well known compound containing phosphate ion is phosphoric acid. Phosphate ions react with ammonium molybdate to produce a characteristic yellow precipitate, ammonium phosphomolybdate. This video explains how to test the presence of phosphate ion in a given salt.
Most of the matter in our surroundings exists as mixtures of two or more components. Examples: Milk, Soil, Sea water. etc. A mixture shows the properties of its constituent elements. The components of a mixture can be separated by physical methods like handpicking, filtration and so on. Sometimes special techniques have to be used for the separation of the components of a mixture. This video explains how to separate the components of a mixture of ammonium chloride, salt and sand.
Lead is a chemical element with symbol Pb. It is found in lead pencil and lead acid battery. Lead is found in many salts like lead nitrate and lead acetate as lead (II) ion. In group I, lead (II) ions are precipitated as their chlorides by adding dilute hydrochloric acid to their solutions. Lead chloride solution in hot water when reacts with potassium iodide solution to form yellow precipitate of lead iodide and potassium chromate to form yellow precipitate of lead chromate. This video explains how to test the presence of group I lead ion in a given salt….
Oxalates are salts of oxalic acid containing oxalate ion. Oxalate ion is a dianion. Upon protonation, oxalate ion forms a commonly known compound, oxalic acid. The commonly known oxalate salts are sodium oxalate, potassium oxalate etc. The calcium metal ion reacts with oxalate ion to form an insoluble precipitate of calcium oxalate, which is the primary constituent of most of the common kind of Kidney stones. This video explains how to test the presence of oxalate ion in a given salt.
Melting point of a solid is defined as the temperature at which a solid changes into liquid. Melting point of a solid indicates the strength of the force of attraction between the particles of the solid. On heating a solid, its molecule absorbs energy in the form of heat and their kinetic energy increases. As the kinetic energy increase the temperature of the solid increases. As a result, the force of attraction between the molecules decreases and the molecules become more and more separated. This increases the potential energy of the molecule and the particles leave their fixed positions and…
An electric circuit is simply a closed loop through which charges can continuously move. An electric circuit basically contains a source of electricity, a load resistance, a switch or a key for turning the circuit on or off at one’s convenience. When two or more resistors are connected such a way that one end of one resistor is connected to the starting end of the other, then the circuit is called a Series Circuit. Since the current has only one path to take, the current through a series circuit is the same through each resistor. The total resistance/effective resistance of…
Respiration is the process during which simple carbohydrates, like glucose, break down into simpler substances and liberate carbon dioxide and energy. The compound used, or oxidized, during respiration is called a respiratory substrate. Carbohydrates, fats, and proteins are examples of respiratory substrates, and carbohydrates are the preferred respiratory substrate among them. Respiration produces a great deal of energy that is needed by plants to grow and stay healthy. Excess sugars produced by photosynthesis that are not needed for respiration and growth are stored as starch which can then be converted back to sugars when needed during periods of low light….
The sour and bitter tastes we find in food are due to the presence of acids and bases. Some naturally occurring acids are: vinegar (acetic acid), citric acid (present in orange and lemon), tartaric acid (present in tamarind), etc. Also our stomach produces hydrochloric acid which helps in the digestion of food. Some commonly used bases are baking soda and tooth paste. Tooth paste is a basic substance used for cleaning the teeth and it neutralizes the excess of acids present in the mouth and prevents tooth decay. This video explains how to study the properties of acids and…
Aluminium is a chemical element in the boron group with symbol Al and atomic number 13. Aluminum has three oxidation states. The most common one is +3. The other two are +1 and +2. One +3 oxidation state for Aluminum can be found in the compound aluminum oxide, Al2O3. In AlO, aluminum monoxide, it has a +2 oxidation state, and AlH has an oxidation state of +1.It is found in various salts like aluminium chloride and aluminium oxide as Al (III) ion. Aluminium ion is precipitated as its hydroxide by adding ammonium hydroxide to its solution. This video explains…
The mosquitoes are a family of small, midge-like flies. Like all flies, mosquitoes go through four stages in their life – egg, larva, pupa, and adult. We call this as the life cycle. Each of these stages is morphologically different from the other, with even the habitat of each stage differing. The first three stages – egg, larva and pupa are largely aquatic, whereas the adult stage is aerial. The eggs are laid one at a time and they float on the surface of the water. Most eggs hatch into larvae within 48 hours. Mosquito larvae live in water from…
The metre bridge, consists of a one metre long wire of uniform cross sectional area, fixed on a wooden block. A scale is attached to the block. Two gaps are formed on it by using thick metal strips in order to make the Wheat stone’s bridge. The metre bridge is operates under Wheat stone’s principle. Here, four resistors P, Q, R, and S are connected to form the network ABCD. In the balancing condition, there is no deflection on the galvanometer. Then, P/q = R/S. This video explains how to verify the laws of resistances in series and parallel….
A slinky is a long helical spring, usually made of steel. It is flexible and has appreciable elasticity. It produces transverse waves when one end is fixed and the other end is stretched and given a jerk at right angle to its length. It produces longitudinal waves when compressions are given at regular intervals of time at the free end of the slinky. A disturbance which propagates through a medium is called wave. This video explains how to determine the velocity of a pulse propagated through a slinky or a stretched string.
The Newton’s Law of Cooling is named after the famous English Physicist Sir Isaac Newton, who conducted the first experiments on the nature of cooling. According to Newton’s Law of Cooling, the rate of cooling of a body is directly proportional to the difference in temperatures of the body (T) and the surrounding (T0), provided difference in temperature should not exceed by 30 °C. This video explains how to study the relationship between the temperature of a hot body and its time of cooling by plotting a cooling curve.