Question

How many bromine atoms are present in 38.7 g of CH2Br2

Answer 1

Number of Br atoms : 2.679 x 10²³

Further explanation

The mole is the number of particles contained in a substance

1 mol = 6.02.10²³

Moles can also be determined from the amount of substance mass and its molar mass

`\tt mol=(mass)/(MW)`

Proust stated the Comparative Law that compounds are formed from elements with the same Mass Comparison so that the compound has a fixed composition of elements

• mass of Br in CH₂Br₂

`\tt mass~Br=(2.Ar~Br)/(MW~CH_2Br_2)* mass~CH_2Br_2\\\\mass~Br=(2.80)/(174)* 38.7=35.59~g`

• mol of Br

`\tt (35.59)/(80)=0.445`

• number of atoms

`\tt 0.445* 6.02* 10^(23)=\boxed{\bold{2.679* 10^(23)}}`