Last seen: Nov 14, 2021
(a) Postulates of Dalton’s atomic theory: (i) All the matter is made up of very small particles called ‘atoms’. (ii) Atoms cannot be divided. ...
Joseph Proust put forward law of proportion in 1779. This law states that the chemical compound always consists of the same elements combined together...
Antonie Lavoisier proposed the Law of conservation of mass which states that ‘Mass can be neither created nor destroyed’ so in a chemical reaction, th...
(a) Molecular mass of hydrogen sulphide (H2S) = 2 x H + 1 x S = (2 + 32) u = 34u (b) Molecular mass of Carbon disulphide (CS2) = 1 x C + 2 x S ...
Molecular mass of hydrogen bromide (HBr) = 1 x H + 1 x Br = (1 + 80) u = 81u
Molecular mass of chloroform (CHCl3) = 1 x C + 1 x H + 3 x Cl = (12 + 1 + 106.5)u = 119.5 u
Molecular mass of Nitric acid (HNO3) = 1 x H + 1 x N + 3 x O = (1 + 14 + 48) u = 63 u
Molecular mass of ethanoic acid (CH3COOH) = 1 x C + 3 x H + 1 x C + 2 x O + 1 x H = 12 + 3 + 12 + 32 + 1 = 60u
(a) Molecular mass of Methanol (CH3OH) = 1 x C + 3 x H + 1 x O + 1 x H = (12 + 3 + 16 + 1)u = 32u (b) Molecular mass of Ethanol (C2H5OH) = 2 ...
(a) Molecular mass of methane (CH4) = 12 + 4 = 16 u (b) Molecular mass of ethane (C2H6) = 2 x 12 + 6 x 1 = 30 u (c) Molecular mass of ethane (C2...
(a) Molecular mass of Hydrogen (H2) = 2 x H = 2 x 1 u = 2 u (b) Molecular mass of oxygen (O2) = 2 x O = 2 x 16 u = 32 u (c) Molecular mass of ch...
Molecular formula of glucose is C6H12O6. Atomic mass of C = 12u Atomic mass of H = 1u Atomic mass of O = 16 u Molecular mass = (6 × 12) + ...
Significance of the formula H2O 1. H2O represents water. 2. It represents one molecule of water. 3. H2O also represents 6.022 x 1023 molecules...
Significance of the formula: 1. A chemical formula represents its name. 2. It represents one molecule of a substance. 3. It gives the number of...
(i) N – one atom of nitrogen (ii) 2N – two separate atoms of nitrogen (iii) N2 – one molecule of nitrogen (iv) 2N2 – two molecules of nitroge...
H2 represents one molecule of hydrogen which is formed by the bonding of two separate hydrogen atoms. 2H represents two separate atoms of hydrogen.
(a) Oxygen gas occurs as a diatomic molecule in nature. (b) Noble gases occur as monoatomic gases in nature.
H2 represents two atoms of hydrogen, S is one atom of sulphur and O4 is four atoms of oxygen.
(a) O - one atom of oxygen (b) 2O - two separate atoms of oxygen (c) O2 - one molecule of oxygen (d) 3O2 - three molecules of oxygen
N2 is the chemical formula of nitrogen gas that shows it is formed by a chemical bond. 2N represents two atom of nitrogen which are not chemically ...