10th Science Most Important Repeated Concepts
𝗣𝗮𝘀𝘀𝗶𝗻𝗴 𝗣𝗮𝗰𝗸𝗮𝗴𝗲
𝗖𝗵𝗲𝗺𝗶𝘀𝘁𝗿𝘆
𝗖𝗵𝗲𝗺𝗶𝗰𝗮𝗹 𝗥𝗲𝗮𝗰𝘁𝗶𝗼𝗻𝘀 𝗮𝗻𝗱 𝗘𝗾𝘂𝗮𝘁𝗶𝗼𝗻𝘀
→Chemical reaction
★ Reactant converted into product.
→Chemical equation
★ Symbolically representation of chemical reaction.
→Balanced chemical equation
★ Same number of atoms in LHS and RHS
Important balanced Chemical equations
★ Na2SO4 + BaCl2 → BaSO4+ 2NaCl
★ CaCO3 → CaO + CO2
★ H2 + Cl2 → 2HCl
★ 2Na + 2H2O → 2NaOH +H2
★ CaO(s) + H2O(l) → Ca(OH)2
★ Mg + 2HCl → MgCl2 + H2
★ CH4(g) + 2O2(g) → 2H2O(g) + CO2(g)
→ Combination reactions
★ Two reactants →one product
Ex: H2 + Cl2 →2HCL
→ Decomposition reaction
★ One reactant → two or more products
Ex: CaCO3 → CaO + CO2
→ Electrolytic decompositin (Electrolysis of water)
★ Cathode - H2
★ Anode - O2
→ Photolytic decomposition
Ex: 2AgCl → 2Ag + Cl2
→ Oxidation
★ Addition of oxygen
Ex: 2Zn + O2 →2ZnO
→ Reduction
★ Removing of oxygen
Ex: ZnO + C →Zn + CO
→ Redox reaction
★ Oxidation and reduction occur in same reaction.
Ex: CuO + H2 → Cu + H2O
→ Displacement reaction
★ More reactive element displace the less reactive element.
Ex: Fe + CuSO4 → FeSO4
Iron more reactive than copper.
→ Double displacement reaction
★ Exchange of ions between reactants.
Ex: Na2SO4 + BaCl2 → BaSO4 + 2NaCl
→ Precipitation reaction
★ Insoluble substance formed in the reaction
Ex: Na2SO4 + BaCl2 → BaSO4 + 2NaCl
Precipitate - BaSO4
Ions - Ba^2+ and SO4 ^ 2-
→ Exothermic reaction
★ Heat released in the reaction
Ex: CaO + H2O → Ca(OH)2 + Heat
→ Endothermic Reaction
Heat absorbed in the reaction
Ex: CaCO3 →CaO + CO2
→ Corrosion
★ Metal + atmosphere substance → Undesirable substance
Ex: Rusting of iron
→ Rancidity
★ Smell /taste of oil/fat containing substance change by oxidation.
Prevention
★ Use Antioxidant
★ Refrigerating.
★ Use Nitrogen gas
★ Pack in air tight container
→ Important Oxidised and Reduced reactants.
★ Na + O2 →Na2O
Oxidized substance - Na
Reduced substance - O2
★ CuO + H2 → Cu + H2O
Oxidized substance - H2
Reduced substance - CuO
★ ZnO + C → Zn + CO
Oxidized substance - C
Reduced substance - ZnO
𝗔𝗰𝗶𝗱𝘀, 𝗕𝗮𝘀𝗲𝘀 𝗮𝗻𝗱 𝗦𝗮𝗹𝘁𝘀
→ Acid.
★ Sour taste
★ Produce H+ ions
★ Blue litmus to red
★ pH below 7
★ Ex: HCl, H2SO4
→Base
★ Bitter taste
★ Produce OH- Ions
★ Red litmus to blue
★ pH above 7
★ Ex: NaOH, KOH, Ca(OH)2...
→Reactions
★ Acid + Metal → Salt + Hydrogen gas
Ex: H2SO4 + Zn → ZnSO4 + H2
★ Acid + Metal carbonate → Salt + water + Carbon dioxide
Ex: HCl + NaHCO3 →NaCl + H2O + CO2
★ Acid + Metal oxide → Salt + Water
2HCl + ZnO →ZnCl2 + H2O
Neutralization reaction
★ Acid + Base →Salt + Water
Ex: NaOH + HCl →NaCl + H2O
→ Some naturally occurring acids
★ Vinegar - Acetic acid
★ Orange - Citric acid
★ Tamarind - Tartaric acid
★ Tomato - Oxalic acid
★ Sour milk (Curd) - Lactic acid
★ Nettle sting - Methanoic acid
★ Ant sting - Methanoic acid
★ Lemon - Citric acid
→Tooth decay
Causes
★ In our mouth, bacteria convert sugar into acid
★ This acid cause tooth decay
Prevention
★ Use toothpaste which is basic and it neutralize the acid
Blood pH: 7.2 to 7.8
Acid rain pH: below 5.6
→ Chloro alkali process
2NaCl + 2H2O→ 2NaOH + Cl2 + H2
Product uses:
NaOH
★ Soaps and detergents
★ Papar making
Cl2
★ Water treatment
★ Swimming pool
★ PVC
H2
★ Fuels
★ Margarine
→ Washing Soda
★ Chemical name - Sodium carbonate
★ Chemical formula -Na2CO3
Uses
★ Manufacture of borax,
★ softening of hard water
→Baking Soda
★ Chemical name - Sodium hydrogen carbonate
★ Chemical formula -NaHCO3
Uses -
★ antacid
★ ingredient of baking powder
→ Bleaching Powder
★ Chemical name - Calcium oxychloride
★ Chemical formula -CaOCI2
Uses -
★ Bleaching clothes
★ oxidizing agents
★ disinfecting water
→ Plaster of Paris
★ Chemical name - Calcium sulphate Hemihydrate
★ Chemical formula -CaSO4.1/2H2O
Uses -
★ Fractured bones
★ Making toys
★ Decorative materials
𝗠𝗲𝘁𝗮𝗹𝘀 𝗮𝗻𝗱 𝗡𝗼𝗻-𝗠𝗲𝘁𝗮𝗹𝘀
→ Physical properties of Metals
★ Sonorous
★ Ductile
★ Malleable
★ Lustrous
★ Conduct heat and electricity
→ Physical Properties of Non-Metals
★ No sonorous
★ No ductile
★ No malleable
★ Poor conductor of electricity
Ductile : Metal can drawn in to thin wire.
Malleable : Metal can beaten in to thin sheet.
→ Chemical properties of metals :
★ Liberates H2 from dilute acids.
★ Metallic oxides are basic in nature.
→ Chemical properties of non-metals :
★ Do not liberate H2 from dilute acids.
★ Oxides of non-metals are acidic in nature.
→ Formation of NaCl
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