Question

How many moles are in a 275g sample of K2CrO3

Answer 1

There are approximately 1.54 moles in a 275 g sample of
`K_2CrO_3`.

Step-by-step explanation:

To find out number of moles, fistly we have to calculate molecular mass of
`K_2CrO_3`.

There are 2 atoms of Potassium 1 atom of Chromium and 3 atoms of oxygen in the given compound.

For molecular mass we have to add the value of mass of 2 atoms of Potassium with mass of 1 atom of Chromium and with mass of 3 atoms of oxygen.

Atomic mass of Potassium = 39

Atomic mass of Chromium = 52

Atomic mass of Oxygen = 16

Now,

Molecular mass of
`K_2CrO_3` =
`2* 39+52+3* 16=78+52+48=178\ gm`

The molecular mass of a compound is the mass of compound in one mole.

To find out the number of moles, we have to divide given mass of compound by its molecular mass.

`Number\ of\ moles=(given\ mass)/(molecular\ mass)`

`Number\ of\ moles=(275)/(178)= 1.54`

Hence the number of moles in 275 gm of
`K_2CrO_3` is 1.54.