Question

some examples of mole concept

Answer 1

answer are above the image

Answer 2

Example: Which one of the following molecules has greatest relative molecular mass.

I. CO

II.SO2

III. Fe2(SO4)3

IV. CaCO

Solution:

I. One CO molecule includes one C atom and one O atom

Molecular mass of CO=(1.12)+(1.16)=28 amu

II. One mole SO2 includes one S atom and two O atoms.

Molecular mass of SO2=(1.32)+(2.16)=64 amu

III. One mole Fe2(SO4)3 includes 2 Fe atoms 3 S atoms and 12 O atoms.

Molecular mass of Fe2(SO4)3=(2.56)+(3.32)+(12.16)=400 amu

IV. One mole CaCO3 molecule includes one Ca atom, one C atom and 3 O atoms.

Molecular mass of CaCO3=(1.40)+(1.12)+(3.16)=100 amu

Thus; Fe2(SO4)3 has greater molecular mass

Including C, most of the elements have isotopes. We must consider atomic masses of all isotopes while writing it in periodic table. Example given below shows how to calculate average atomic mass of elements having isotopes.

MassX=M(X1).%X1/100+M(X2).%X1/100+...

where; MassX is the average mass of X element

M(X1) and M(X2) are masses of isotopes

%X1 and %X2 are Percentages of atomic masses of X element in nature.

Example: Relative atomic mass of one element is 44,1 amu and it has two isotopes.If one of the isotopes has atomic mass 42 amu and percentage of it is 30%, find the atomic mass of second isotope.

Solution:

If one of the isotopes has 30% of atomic mass, other isotope has 70% of atomic mass.

MassX=M(X1).%X1/100+M(X2).%X1/100+...

44,1=42.30/100+M(X2).70/100

M(X2)=45 amu
-HOPE THIS WILL HELP U <3