Question

Question 2 Which has more number of atoms, 100 grams of sodium or 100 grams of iron (given, atomic mass of Na = 23 u, Fe = 56 u)?

Class 9 - Science - Atoms and Molecules Page 42

Answer 1

Heya !

Here is your answer =========================================================================

>> In order to solve this problem, we should convert 100 grams of sodium into moles of sodium, and also 100 grams of iron into moles of iron. The element having more moles will have more atoms. Please note that since the atomic mass of sodium is 23 u , the molar mass of sodium will be 23 g / mol. Similarly, since the atomic mass of iron is 56 u , the molar mass of iron will be 56 g / mol. We will now calculate the moles of sodium atoms (Na) and iron atoms (Fe), one by one.

(i) Mass of sodium = Mass of sodium / Molar mass of sodium

= 100/23

= 4.34

(ii) Moles of iron = Mass of iron / Molar mass of iron

= 100/56

= 1.78

We find that 100 grams of sodium contain 4.34 moles of atom whereas 100 grams of iron contain 1.78 moles of atoms. Since 100 grams of sodium has more moles, it contains more atoms than 100 grams of iron.

Answer 2

Answer:

the number of moles of 100 g Na atoms =100/23 =4.35 moles

the number of moles in 100 g of Fe atoms = 100/56 = 1.76 moles

As we know , the one - mole atoms contains 6.022 multiply 10 ^23 atoms .

so , more the number of moles , more the number of atoms . and hence 100 g pf Na atoms has a greater number of atoms than 100 g Fe .