How many atoms of chromium are there in 72.65 kg of potassium dichromate?

Answer 1

Potassium dichromate K2Cr2O7
Mr of K2Cr2O7 = 294
Moles of K2Cr2O7 in 72.65 kg = (72.65 x 1000)/294 = 247.1 ( to 4 s.f.)
For every 1 mole of K2Cr2O7, there are 2 moles of K atoms, 2 moles of Cr atoms and 7 moles of O atoms.
Hence form 247.1 moles of K2Cr2O7, there are (247.1 x 2 = 494.2) moles of Cr atoms.
1 mole of any substance contains 6.02 x 10^23 (Avogadro's constant).
Hence 494.2 moles of Cr atoms is equivalent to
494.2 x (6.02 x 10^23) = 2.98 x 10^26 Cr atoms (to 3 s.f.)

Hope this helps :)

Answer 2

molecular weight of pottasium dichromate comes out to be 294 gm/mole.

so 294 gms of k2cr2o7 contains 104 gm of chromium.

if we convert into kgs, then 0.294 kgs of k2cr2o7 contains 0.104 kgs of chromium.

therfore 72.69 kgs will contain how many kgs of chromium.

on cross multiplication answer comes out to be 25.69 kgs of chromium.

now as per avagadro's hypothesis, 52 gms of chromium contains
6.022 x 10^23 atoms of chromium

therefore converting 25.69 kgs into gms so 2569 grams of chromium will contain how many atoms
'
on cross multiplication we get answer as 2976.14 x 10^23 atoms of chromium

i hope i have solved ur problem

Answer 3

Please, do your own homework.