Question

Calculate the mass of tetraborane (B4 H10) that contains a billion (1.0 x 10 *9) boron atoms. Be sure your answer has a unit symbol if necessary, and round it to significant digigits.

Answer 1

Answer:

a billion boron atoms are contained in a mass m= 2.21*10⁻¹⁴ gr of tetraborane

Explanation:

Since there are an Avogadro number (N= 6.023*10²³ molecules/mole) of molecules of tetraborane in a mole of tetraborane , and per each molecule there are 4 atoms of B . Then

number of moles n = a/(4*N)

where a= number of atoms

the corresponding mass of tetraborane m is

m= n*M

where M= molecular weight of tetraborane = 53.32 g/mol

then

m= n*M = a*M/(4*N)

replacing values

m= a*M/(4*N)= 1.0*10⁹ atoms of B * 53.32 gr/mole /( 4 atoms of B/molecule* 6.023*10²³ molecules/mole ) = 2.21*10⁻¹⁴ gr

m= 2.21*10⁻¹⁴ gr