UKPCS Science Chemistry: Plaster of Paris #14

Oracle IAS, the best coaching institute for UPSC/IAS/PCS preparation in Dehradun brings to you UKPCS Science Chemistry (paper 6). 

PLASTER OF PARIS

Gypsum plaster, or plaster of Paris, is produced by heating gypsum to about 300 °F (150 °C)

CaSO4·2H2O + heat → CaSO4·0.5H2O + 1.5H2O (released as steam). Continue reading “UKPCS Science Chemistry: Plaster of Paris #14”

UKPCS Science Chemistry: Bleaching Powder #13

Oracle IAS, the best coaching institute for UPSC/IAS/PCS preparation in Dehradun brings to you UKPCS Science Chemistry (paper 6). 

Bleaching Powder

Calcium hypochlorite is an inorganic compound with formula Ca(ClO)2. As a mixture with lime and calcium chloride, it is marketed as chlorine powder or bleach powder for water treatment and as a bleaching agent. It strongly smells of chlorine, owing to its slow decomposition in moist air. It is not highly soluble in water and is more preferably used in soft to medium-hard water. Continue reading “UKPCS Science Chemistry: Bleaching Powder #13”

UKPCS Science Chemistry: Baking soda #12

Oracle IAS, the best coaching institute for UPSC/IAS/PCS preparation in Dehradun brings to you UKPCS Science Chemistry (paper 6). 

Sodium bicarbonate is a white solid that is crystalline but often appears as a fine powder. It has a slightly salty, alkaline taste resembling that of washing soda (sodium carbonate). The natural mineral form is nahcolite. Continue reading “UKPCS Science Chemistry: Baking soda #12”

UKPCS Science Chemistry: Sodium carbonate #11

Oracle IAS, the best coaching institute for UPSC/IAS/PCS preparation in Dehradun brings to you UKPCS Science Chemistry (paper 6). 

Sodium carbonate (also known as washing soda, soda ash and soda crystals, and in the monohydrate form as crystal carbonate), Na2CO3, is the water-soluble sodium salt of carbonic acid. Continue reading “UKPCS Science Chemistry: Sodium carbonate #11”

UKPCS Science Chemistry: Water purification #9

Oracle IAS, the best coaching institute for UPSC/IAS/PCS preparation in Dehradun brings to you UKPCS Science Chemistry (paper 6). 

Water purification

Water purification is the process of removing undesirable chemicals, biological contaminants, suspended solids and gases from water. The goal is to produce water fit for a specific purpose. Most water is disinfected for human consumption (drinking water), but water purification may also be designed for a variety of other purposes, including fulfilling the requirements of medical, pharmacological, chemical and industrial applications. The methods used include physical processes such as filtration, sedimentation, and distillation; biological processes such as slow sand filters or biologically active carbon; chemical processes such as flocculation and chlorination and the use of electromagnetic radiation such as ultraviolet light. Continue reading “UKPCS Science Chemistry: Water purification #9”

UKPCS Science Chemistry: Properties of water #8

Oracle IAS, the best coaching institute for UPSC/IAS/PCS preparation in Dehradun brings to you UKPCS Science Chemistry (paper 6). 

What are the Main Properties of Water?

This article will discuss the five main properties of water:

  1. Its attraction to polar molecules
  2. High-specific heat
  3. High heat of vaporization
  4. The lower density of ice
  5. High polarity

Continue reading “UKPCS Science Chemistry: Properties of water #8”

UKPCS Science Chemistry: pH,neutral solution,carbonates #7

Oracle IAS, the best coaching institute for UPSC/IAS/PCS preparation in Dehradun brings to you UKPCS Science Chemistry (paper 6). 

  • pH
    • pH (potential of hydrogen) is a scale of acidity from 0 to 14. It tells how acidic or alkaline a substance is.
    • More acidic solutions, have lower pH. More alkaline solutions, have higher pH. Substances that aren’t acidic or alkaline (that is, neutral solutions) usually have a pH of 7.
    • Acids have a pH that is less than 7. Alkalis have a pH that is greater than 7.pH is a measure of the concentration of protons (H+) in a solution.
    • Typical indicators are phenolphthalein, methyl orange, methyl red, bromothymol blue, and thymol blue. They each change colour at different points on the pH scale, and can be used together as a universal indicator.
    • Another way is to use litmus paper, which is based on a natural pH indicators.

Continue reading “UKPCS Science Chemistry: pH,neutral solution,carbonates #7”

UKPCS Science Chemistry: Acid, Bases, Salts and buffer #6

Oracle IAS, the best coaching institute for UPSC/IAS/PCS preparation in Dehradun brings to you UKPCS Science Chemistry (paper 6). 

Acid, Bases, Salts and buffer

  • Acids have a pH of less than 7. Acid – substances that ionize (release charged particles when dissolved) in water solution to produce hydrogen ions, H+ , or free protons ie Donates protons.
    • The stronger the acid, the lower the pH number. Acids turn blue litmus paper red. They turn universal indicator red if they are strong, and orange or yellow if they are weak.
  • Bases have a pH of more than 7. Base – substances that ionize in water solution to produce hydroxide ions, OH- ie accepts protons. When bases are dissolved in water, they are known as alkalis.
    • Substances that can react with acids and neutralise them to make a salt and water are called bases. They are usually metal oxides or metal hydroxides. For example, copper oxide and sodium hydroxide are bases.
    • Bases that dissolve in water are called alkalis. Copper oxide is not an alkali because it does not dissolve in water. Sodium hydroxide is an alkali because it does dissolve in water.
    • Alkaline solutions have a pH of more than 7. The stronger the alkali, the higher the pH number. Alkalis turn red litmus paper blue. They turn universal indicator dark blue or purple if they are strong, and blue-green if they are weak.
  • Salts are made when an acid reacts with a base, carbonate or metal. Salt – a crystalline compound composed of the negative ion of an acid and the positive ion of a base. The name of the salt formed depends on the metal in the base and the acid used. For example, salts made using hydrochloric acid are called chlorides.
    • When acids react with bases, a saltand water are made. This reaction is called neutralisation. In general:

acid + metal oxide → salt + water

acid + metal hydroxide → salt + water

  • Buffer – a solution that can receive moderate amounts of either acid or base without the significant change in its pH.
    • A buffer solution is an aqueous solution made up of a mixture of a weak acid and its conjugate base or a weak base and its conjugate acid. The solution resists changes in pH when a small amount of an acid or alkali is added to it. Buffer solutions are critical in keeping the correct pH for enzymes.

      Contact us for:-
      •IAS coaching in Dehradun
      UKPCS/UPPCS coaching in Dehradun
      Current Affairs classes in Dehradun
      •For getting detailed feedback on your answers and improve answer writing
      •Phone Number:- 9997453844

UKPCS Science Chemistry: Physical change and Chemical change #5

Oracle IAS, the best coaching institute for UPSC/IAS/PCS preparation in Dehradun brings to you UKPCS Science Chemistry (paper 6). 

Comparison Chart- Physical change and Chemical change

BASIS FOR COMPARISONPHYSICAL CHANGECHEMICAL CHANGE
MeaningPhysical change refers to a change in which the molecules are rearranged but their internal composition remains same.Chemical Change is a process in which the substance transforms into a new substance, having different chemical composition.
ExampleTearing of paper, melting/freezing of water, cutting of trees, etc.Burning of wood/trees/paper, rusting of iron, setting of curd, etc.
NatureReversibleIrreversible
Original matterCan be recoveredCannot be recovered
InvolvesChange in physical properties of the substance, i.e. shape, size, color etc.Change in chemical properties and composition of the substance.
Product FormationNo new product is formed.New product is formed.
EnergyAbsorption and evolution of energy do not take place.Absorption and evolution of energy take place, during reaction.

Continue reading “UKPCS Science Chemistry: Physical change and Chemical change #5”

UKPCS Science Chemistry: Chemical compounds #4

Oracle IAS, the best coaching institute for UPSC/IAS/PCS preparation in Dehradun brings to you UKPCS Science Chemistry (paper 6). 

CHEMICAL COMPOUNDS

  • Any substance consisting of two or more different types of atoms (chemical elements) in a fixed proportion of its atoms (i.e., stoichiometry) can be termed a chemical compound.
  • Ionic compounds are compounds composed of ions, charged particles that form when an atom (or group of atoms, in the case of polyatomic ions) gains or loses electrons.
  • cationis a positively charged ion
  • An anionis a negatively charged ion.

Continue reading “UKPCS Science Chemistry: Chemical compounds #4”