How many molecules are present in (2)a) 9 g of water? (Atomic mass of

1.	How many molecules are present in (2)a) 9 g of water? (Atomic mass of H-lu. O-l6u)b) 17g of NH3? (Atomic mass of N- 14u)
Answer» Given weight = 9g molecular weigh = 2 + 16= 18g no. of molecules = 9/18=0.5 molecules The molar mass of nitrogen is 14 g while that of hydrogen is 1g. The chemical formula for ammonia is NH3, so the molar mass of ammonia will be = molar mass of nitrogen + 3 X (molar mass of hydrogen) = 14 + 3 X (1) = 17 g Thus the molar mass of ammonia is 17 g. This means that there are 6.023 X 1023molecules of ammonia present in 17 g of ammonia. That is 17 g of NH3= 6.023 X 1023molecules of ammonia

How many molecules are present in (2)a) 9 g of water? (Atomic mass of H-lu. O-l6u)b) 17g of NH3? (Atomic mass of N- 14u)

Answer»

Given weight = 9g molecular weigh = 2 + 16= 18g no. of molecules = 9/18=0.5

molecules

The molar mass of nitrogen is 14 g while that of hydrogen is 1g. The chemical formula for ammonia is NH3, so the molar mass of ammonia will be

= molar mass of nitrogen + 3 X (molar mass of hydrogen)

= 14 + 3 X (1) = 17 g

Thus the molar mass of ammonia is 17 g. This means that there are 6.023 X 1023molecules of ammonia present in 17 g of ammonia. That is

17 g of NH3= 6.023 X 1023molecules of ammonia