Question

What is the mass of $5.60$ mol $NaOH$ ?

Answer 1

The elements combine to form molecules. Sodium, oxygen and hydrogen combine to form a compound known as sodium hydroxide. Sodium hydroxide is a strong base and has the molar mass of $40$ atomic mass units. Given that the number of moles of sodium hydroxide is $5.60$ mol. The mass can be obtained from the product of the number of moles and molar mass.
Formula used:
$m = n \times M$
$m$ is mass
$n$ is number of moles
$M$ is molar mass

Complete answer:
Given compound is sodium hydroxide. It has the molecular formula of $NaOH$ from the molecular formula it was known that the compound consists of sodium, oxygen and hydrogen atoms.
Sodium is an element with atomic number $11$ and has the molar mass of $23$ amu.
Oxygen is an element with atomic number $8$ and has the molar mass of $16$ amu.
Hydrogen is an element with atomic number $1$ and has the molar mass of $1$ amu.
Thus, the molar mass of sodium hydroxide will be equal to the sum of the molar masses of sodium, oxygen and hydrogen atoms.
Given that the number of moles of sodium hydroxide is $5.60$ moles.
From the definition of number of moles, the number of moles of a compound is the ratio of the mass of the compound to the molar mass of the compound.
Substitute the molar mass and number of moles in the above formula.
$m = 5.6 \times 40 = 224gm$
Thus, the mass of $5.60$ mol $NaOH$ is $224gm$

Note:
All the elements in the periodic table will not have the mass number equal to the double of atomic number. The sodium is an element with atomic number $11$ and has the molar mass of $23$ amu but not $22$ amu. This is due to the difference in the neutron number. Thus, while calculating the molar mass exact molar mass should be taken.