Question

A. How many molecules are present in a sample of this compound that contains 2.98 moles of 2-methyl-1-butanol?

B. How many moles of 2-methyl-1-butanol are present in a sample of this compound that contains 7.15x10^22 carbon atoms?

C. How many carbon atoms are present in 1.48 moles of this compound (pentanal)?

D. How many moles of pentanal are present in 1.82x10^22 molecules of this compound?

Answer 1

One mole of every substance contains Avogadro no. of particles.

Avogadro no.,N_A=6.022x10²³

(A)No. of molecules in 1 mole of 2-methyl-1-butanol = 6.022x10²³

No. of molecules in 2.98 moles of 2-methyl-1-butanol = 6.022x10²³ x 2.98 =1.79 x10²⁴

(B) 1 molecule of 2-methyl-1-butanol contains 5 carbon atoms

Therefore, No. of carbon atoms in 1 mole of 2-methyl-1-butanol = 5 x  6.022x10²³

  =3.011x10²⁴

3.011x10²⁴ carbon atoms are present in 1 mole of  2-methyl-1-butanol

No. of moles of  2-methyl-1-butanol containing 7.15x10²² carbon atoms= (1/3.011x10²⁴) x  7.15x 10²²

  =0.02375 moles

(C) No. of carbon atoms in 1 molecule of Pentanal =5

No. of carbon atoms in 1 mole of Pentanal =5x6.022x10²³ = 3.011x10²⁴

No. of carbon atoms in 1.48 moles of Pentanal =5x6.022x10²³ = 3.011x10²⁴ x1.48

=4.456x10²⁴

(D) 6.022x10²³ molecules are present in 1 mole of Pentanal.

No. of moles of Pentanal in 1.82x10²² molecules=(1/ 6.022x10²³) x 1.82x10²²

= 0.03022 moles

(

1/3.011x10²⁴) x  7.15x 10²² moles of  2- methyl -1- butanol.

=0.02375 moles of  2- methyl -1- butanol.