What are The Basic Things to Know in Chemistry?
What are the basic things to know in Chemistry? This is a common question asked by so many students. i have pulled answers to some interesting chemistry questions.
1. State differences between metals and non-metals
METALS | NON-METALS |
Metals are lustrous Metals are malleable, ductile and sonorous Metals have high densities Good conductors of heat/electricity Metals are reducing agents Metals tend to form ionic compounds | Non-metals are non-lustrous Non-metals are not malleable, ductile and sonorous Non-metals have low densities Poor conductors of heat /electricity Non-metals are oxidizing agents Non-metals form covalent compounds |
2. State differences between mixtures and compounds
MIXTURES | COMPOUND |
Maybe homogeneous or heterogeneous Constituents are not chemically bound together Constituents can be added in any ratio The Properties of a mixture are the sum of the individual constituents | Always homogeneous Component elements are chemically bound together Components are present in a fixed ratio The properties of a compound differ entirely from those of its component elements |
3. State differences between a physical change and chemical change
PHYSICAL CHANGE | CHEMICAL CHANGE |
Easily reversible No new substance has formed No change in the mass of substances involved Does not involve any great heat change | Not easily reversible New substances formed Change in the mass of substances involved Involves great heat change |
4. Mention two Criteria for purity of a substance
a. fixed melting and boiling point
b. A single spot on a chromatogram (colored substance)
5. Mention 3 factors that affect solubility of a solid (salt)
a. Temperature b. nature of solvent c. size of the particle
6. Mention the physical properties on which these separation methods depend on
Separation methods | Physical property |
Sieving Distillation Sublimation Filtration / Decantation | The difference in particle size Difference in boiling points Ability of a substance to sublime Insoluble solid in water |
7. State the contributions of the following scientists
Scientists | Discoveries |
John Dalton J.J Thomson Ernest Rutherford Niels Bohr James Chadwick Erwin schrodinger Dmitriv mendeleev Moseley | Billiard ball Electron and proton(plum pudding model) Nucleus Energy l evels/shells/orbits/quanta Neutron Electron cloud Periodic table Atomic number |
8. State three statements of Dalton’s atomic theory
Statements of Dalton’s atomic theory |
Atom cannot be created nor destroyed elements are made up of small indivisible particles called atoms When atoms react, they do so in simple ratio Atoms of an element look alike and differ from atoms of other elements |
9. State three modifications of Dalton’s atomic theory
Modifications of Dalton’s atomic theory |
Isotopy-atoms of the same element do not always look alike Nuclear reaction: during nuclear reactions, atoms can be created or destroyed Macromolecules/starch: in macromolecules atoms are not combined in simple ratios |
10. State three properties of ionic compound/electrovalent compounds
Ionic compounds/electrovalent compounds Ionic compounds have high melting and boiling points They are soluble in water They conduct electricity in molten or aqueous form they are usually solids at room temperature |
11. State three properties of covalent compounds
Covalent compounds Covalent compounds have low melting and boiling pointsCovalent compounds are not soluble in water but soluble in non-polar solvents they do not conduct electricity They are usually volatile liquids or gases at room temperature |
12. State three assumptions or statements of kinetic theory of gases
Assumptions of kinetic theory of gases The gas molecules move randomly in a straight lineThe collisions of the gas molecules are perfectly The actual volume occupied by the gas molecules themselves is negligible compared to the actual volume of the container. Cohesive forces between the gas molecules are negligible The temperature of the gas is a measure of the average kinetic energy of the gas particles |
13. State 3 uses of diamond
Uses of Diamond | Reasons behind the uses |
Used as drills for mining Used as abrasives to sharpen other tools Used in cutting glass and metals Used in making jewellery Used as pivots in precision instruments | Because it is hard and dense Because it is hard and dense Because it is hard and dense Because it has a high refractive index and dispersion power Because it is hard and dense |
14. State the uses of graphite
Uses of graphite | Reasons behind the uses |
Used as an excellent dry lubricant Good conductor of electricity Used as electrodes in electrolytic cells and electroplating Used to line crucibles Used as pencil leads Used as pigment in paints | Layers can slide over another easily Presence of mobile electrons Inert and conducts electricity Withstand high temperature Marks paper and can mix with clay Black color |
15.Mention 4 components of destructive distillation of coal
Components of coal | Uses |
Coke Ammoniacal liquor Coal tar Coal gas | Used as Fuel Used in making Fertilizer Making chemicals e.g Paints, dyes,insecticides,drugs and explosives Used as a Gaseous fuel |
16. State 4 periodic properties
Periodic properties |
ionization energy Electron affinity Electronegativity/electropositivity Atomic radius Melting and boiling point |
17. State three factors that govern the periodic properties
Size of nuclear charge Distance of outermost electron from the nucleus Shielding effect/screening effect |
18.State three factors that affect preferential discharge of ions during electrolysis
1. Position of ion in the electrochemical series 2. Nature of electrode 3. concentration of ions |
18. State three applications of electrolysis
1. Extraction of elements 2. Purification of metals 3. Electroplating of one metal by another 4. Preparation of certain important compounds like NaOH etc |
19. State three factors that emf of a cell depends on.
The emf of a cell depend on Concentration of ionsTemperatureDistance between the two ions in the electrochemical series |
20. Mention two functions of the salt bridge
1. Salt bridge connects two half cells 2. a channel for the exchange of ions 3. it completes the circuit |
21. State two differences between primary cell and secondary cells
Primary cells | Secondary cells |
Cannot be recharged High internal resistance Irreversible reaction Cheap | Can be recharged and reused Low internal resistance Reversible reaction Expensive |
22. Give two examples of primary cells and two examples of secondary cells
Primary cells | Secondary cells |
Daniel cell Leclanche cell | Lead-acid accumulator Nickel-iron (Ni-Fe) cell |
23.state two conditions for spontaneity of a reaction
Positive entropy, low enthalpy Free Gibbs energy must be negative |
24. state six factors that affect rate of a reaction
1. Temperature 2. Nature of reactants 3. Surface area 4. Concentration /pressure for gases 5. Presence of light 6. Presence of a catalyst |
25. State the three factors that influence or govern the factors affecting the rate of reaction
Energy content of the particles Frequency of collisions Activation energy of the particles |
25. state the factor that affects equilibrium constant
Temperature |
26. State three applications of solubility curves
1. Enables pharmacists to determine the amount of solid drugs that must be dissolved in a given solvent 2. Enables chemists and researchers to determine the most suitable solvents to be used at different temperatures for extraction of chemicals 3. Applied in separating or purifying mixtures |
27. State three factors that affect equilibrium or rate of attaining equilibrium
1. Temperature 2. Pressure 3. Concentration |
28. State four properties of a system in equilibrium
1. A chemical system can only be achieved in a closed system 2. A chemical equilibrium has both the forward and backward reaction 3. A chemical equilibrium is dynamic in nature(concentrations of reactants and product remain constant) 4. A catalyst may be used to alter the time required to attain equilibrium |
29. State the four quantum numbers and their effects
Principal quantum number Azimuthal quantum number Magnetic quantum number Spin quantum number |
30. state the optimum conditions for ammonia production/Haber process
Temperature of 4500C Pressure of 200 atm Finely divided iron as catalyst |
31. state the optimum conditions for sulphuric acid production/contact process
The temperature of 4500C Pressure of 1 atm Vanadium V oxide (V2O5) as catalyst |
32. State two differences between burning and rusting
1. Rusting is a slow process while burning is a rapid process 2. water is required for rusting while burning hardly take place in the presence of water 3. Heat given in rusting is small while the heat given out in burning is much 4. Rusting involves iron while burning may not |
33. State the similarities between rusting and burning
1. Both are oxidation processes because they need oxygen 2. Both give out heat |
34. State the effects of temporary hardness
Furring of kettles and boilers Stalagmites and stalactites |
35. State the advantages of hard water
1. Hard water tastes better 2. Builds strong teeth in children 3. Hard water helps animals such as snails and crabs to make their shells 4. Hard water can be supplied in pipes made of lead |
36. State two disadvantages of hard water
1. Hard water wastes a lot of soap 2. hard water causes furring of kettles and boilers 3, Hard water cannot be used in dyeing and tanning |
37.Mention two properties of water
1. Boiling point of 1000C 2. Freezing point of o0C 3. Colorless, odourless and tatsteless 4. Density of 1 g/dm3 at 250C |
38. State the solubility rule
Solubility rule All salts of K, Na, NH4+ are soluble All nitrates are solubleAll sulphates are soluble except BaSO4, PbSO4, CaSO4 All chlorides, iodides and bromides are soluble except AgCl,AgI,AgBr, PbCl2, PbBr2, PbI2, All sulphides, hydroxides and carbonates are insoluble except K2CO3, K2S, KOH, Na2CO3,NaOH, Na2S |
39. state two differences between the colloidal solutions and true solutions
True solutions | Colloidal solutions |
Solution can be dialyzed Solution do not scatter light | Cannot be dialyzed Solution scatter light |
40. State the common solutes and common solvents
Solutions | Components |
Antifreeze Tincture of iodine Soda water | Ethanol in water Iodine dissolved in ethanol Carbon IV oxide dissolved in water |
41. Give two examples of polar and non-polar molecules
Polar molecules | Non-polar molecules |
Water Trichloromethane Ammonia All ionic compounds | Benzene, normal alkanes |
42. Mention three instruments used in detecting radiations
Scintillation counter Diffusion cloud chamber Geiger Muller counter |
43. uses of common radioisotopes
1. Iodine 131 used in treating thyroid disorder 2. Uranium 235 used in making nuclear fuel 3. cobalt 60 4. carbon 14 used in archeology for dating 5 cobalt 60 used in cancer treatment 6. Nickel 63 used to detect explosives |
44. State two applications of nuclear fission and nuclear fusion
Nuclear fission Supplies energy | Nuclear fusion Supplies energy Hydrogen bomb |
45. Mention four alloys and their component elements
Alloys | Component elements |
Brass Bronze Durualumin Steel Stainless steel Permallory Soft solder Soft solder II | Copper and zinc Copper and tin Aluminum, copper, magnesium, and manganese Iron and carbon Iron, chromium and nickel Iron and nickel Lead and tin Lead, tin and antimony |
There are other important facts to note in Chemistry and I strongly recommend you keep on checking as will be updating this post regularly