Question

Explain the following: Molecule Atomic mass Avogadro's Number Mole Concept

Answer 1

ATOMIC MASS -1 atomic mass unit is defined as a mass exactly equal to1/12th the mass of 1 carbon-12 atom. MOLECULAR MASS - It is the sum of atomic masses of the element present in a molecule. for example : In the case of H2O , Ans. 2(1) + 16 = 18 MOLE CONCEPT 1mole is the amount of the substance that contain as many particles as there are atoms in exactly 12g of the 2^C isotope . Always put 1 mole = 6.022* 10^23. 1 mole of oxygen atom contains 6.022*10^23 atom wch weighs 16 g . 1 molecule of O2 contains 6.022*10^23 molecules wch weighs 32 g. U may understand it further by an example ..see ..suppose the question is to calculate the mass of an atom of silver, Ans . 1 mole =6.022*10^23 =108g . Mass of 1 atom = 108/6.022*10^23 =108*10^-23/6.022 Now after solving this ..we will get 17.93 * 10^-23. if the question is to calculate the mass of a molecule of CO2 , in this also u may follow the same steps as given above. Now , if the question is to calculate the number of molecules in 34.2g of cane sugar (C12H22O11).. Ans. 6.022 * 10^23 = it's molar mass. =12(12)+22(1)+11(16)=342g. So , 342g = 6.022*10^23 molecules. 1g = 6.022*10^23/342 therefore , 34.2g = 6.022*10^23 /342 *34.2 = 6.022*10^23 . HOPE IT HELPED :) Regards ilml