Question

What is the mass of –
(A) 1 mole of nitrogen atom.
(B) 4 mole of aluminium atoms (Atomic mass of aluminium = 27)
(C) 10 moles of sodium sulphite ( $N{a_2}S{O_3}$ )

Answer 1

Hint:In order to solve these types of questions we should know the formula of because these are simply formula based questions by just transferring one value:

Formula used:According to formula: $$number of moles = given mass / molar mass$$

Complete step-by-step solution:These questions can be solved just by putting the values in the formula No. of moles of the substance = given mass of the substance / molar mass (atomic mass) of that substance.
(A) 1 mole of nitrogen atom It is given that 1 mole of nitrogen and we know that the atomic mass (molar mass or atomic mass or molecular mass) of the nitrogen is 14.Now we can see that according to the question two things are known and remaining 1 is unknown so it can be calculated by simply interchanging their sides.
Number of moles = given mass / molar mass
Putting all the values in equation:
1 = given mass / 14
On further solving:
Given mass = 14g.
Hence the mass of one mole of nitrogen will be 14 grams.
(B) 4 moles of aluminum atoms (atomic mass of aluminium = 27)
It is given 4 moles of aluminium atoms and also given its atomic mass which is 27.
Now we can see that according to the question two things are known and the remaining 1 is unknown so it can be calculated by simply interchanging their sides.
Number of moles = given mass / molar mass
Putting all values in equation:
4 = given mass / 27
On further solving we get:
Given mass = 27*4
Given mass = 108g.
Hence the mass of 4 mole of nitrogen will be 108 grams.
(C) 10 moles of sodium sulphite ( $N{a_2}S{O_3}$ )
It is given that 10 moles of sodium sulphite and we can calculate the molar mass of sodium sulphite $N{a_2}S{O_3}$ which we will calculated:
To find the molar mass of sodium we need molar mass of
Na = 23
S = 32
O = 16
In sodium sulphite there are 2 Na, 1 S and 3 O so the molar mass of $N{a_2}S{O_3}$ will be
23*2 = 46 as two Na are there in formula
32*1 = 32 as one S is there in formula
16*3 = 48 as three O are there in formula
By adding all these 46+32+48=126.
The resultant molar mass $N{a_2}S{O_3}$ will be 126 amu.
Now putting all these values in formula:
10 = given mass / 126
On further solving we get:
Given mass = 126*10
Given mass = 1260g.
Hence the mass of 10 moles of sodium sulphite will be 1260 grams.

Note:While solving these types of questions we need to learn atomic mass of some of the light weighted elements and some important elements rather than it we need not to memorise them all them will be given in questions where these are required.