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

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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.

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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.

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