Calculate the total number of atoms in 0.5 mole
of K2 Cr2 O7
Answers
What is the number of atoms in 0.5 mol of K2Cr2O7?
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Atomicity —— number of total atoms present in a compound
no. of atoms = atomicity × moles × 6.022×10^23
no. of atoms = (2+2+7) × 0.5 × 6.022 × 10^23
no.of atoms = 11 × 0.5 × 6.022 × 10^23
no.of atoms = 33.121 × 10^23
no.of atoms = 3.3121 × 10^24
So there are 3.3121 × 10^24 atoms in K2Cr2O7
If we are finding the number of oxygen (O) in given compound we take atomicity as a ‘7′ because there are 7 oxygen atoms present . Then fill values in formula to find number of oxygen atoms in K2Cr2O7 .And for other elment i.e Cr or K also follows same rules.
How to find the number of molecules present in a compound ? We know that 1 mole of any substance contain avogadro (6.022×10^23) molecules.Then 'n' moles of any substance contains “ n×6.022×10^23 ” molecules.
No. of molecules = number of moles × 6.022×10^23 molecules.
How to find the volume of the compound if numbers of moles are givine ?we know that 1 mole of any substances contains “ 22.7 liter ” at S.T.P(Standard Temperature and Pressure i.e Temperature = 0°C and pressure = 1bar ) then ' n ' moles of any substance contains “ n×22.7 l ” volume.i.e
Volume = number of moles × 22.7 l
If you have 0.5 moles of K2Cr2O7, then you just multiply the number of moles by avogadro's number
= (0.5)(6.022x1023) = 3.011x1023 molecules.
Since there are 11 atoms per molecule (2+2+7), then you just multiply 3.011x1023 by 11 and you get 3.3121x1024 atoms.