Question

How many moles are in a 275g sample of K2CrO3

Answer 1

Answer:

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

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 $K_2CrO_3$ = $2\times 39+52+3\times 16=78+52+48=178\ gm$

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.

$Number\ of\ moles=\frac{given\ mass}{molecular\ mass}$

$Number\ of\ moles=\frac{275}{178}= 1.54$

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