Create successful ePaper yourself
Turn your PDF publications into a flip-book with our unique Google optimized e-Paper software.
Atoms and Molecules<br />
3.3<br />
MODULE - 2<br />
Matter in our Surroundings<br />
1. 1 mole of a substance contains 6.023 × 10 23 molecules of that substance i.e<br />
1 mole of a substance = 6.023 × 10 23 molecules of that substance.<br />
2. Molecular mass is the sum of atomic masses of all the atoms present in that<br />
molecule.<br />
Notes<br />
Molecular mass is the mass of one molecule whereas molar mass is the mass<br />
of 1 mol or 6.023 × 10 23 elementary entities (atoms, molecules, ions)<br />
3. C(s) + O 2 ⎯⎯→ CO 2<br />
1 mol 1 mol 1 mol of CO 2 (44g)<br />
of C (12g) of O 2 (32g)<br />
12 g of carbon gives 1 mole of CO 2<br />
18g of carbon will give 1.5 mole of CO 2<br />
4. Molar mass of NaCl = ( 23.0 + 35.5 )g mol -1<br />
3.4<br />
= 58.5 g mol -1<br />
1. (i) H 2 S<br />
(ii) NH 3<br />
(iii) MgO<br />
2. (i) KI, Potassium iodide<br />
(ii) Na 2 SO 4 , Sodium Sulphate<br />
(iii) AlCl 3 , Aluminium Chloride<br />
3. (i) HgCl 2<br />
(ii) Pb 3 (PO 4 ) 2<br />
(iii) BaSO 4<br />
SCIENCE <strong>AND</strong> TECHNOLOGY<br />
69
Change language