Question

Calculate the number of moles of zinc in 23.3g.
(A) 0.37 moles
(B) 0.36 moles
(C) 0.5 moles
(D) 0.53 moles

Answer 1

So, in order to calculate the number of moles of any substance present in the sample, we simply divide the given weight of the substance by its molar mass. Where 'n' is the number of moles, 'm' is the given mass and 'M' is the molar mass: $n=\dfrac{m}{M}$,

Complete step by step solution:
We have been provided with 23.3 g of zinc,
We need to find the number of moles associated to it:
So, for that,
The mole is the unit of measurement for the amount of substance in the International System of Units. A mole of a substance or a mole of particles is defined as exactly $6.02214076\times {{10} ^ {23}}$ particles, which may be atoms, molecules, ions, or electrons. In short, for particles $1mol=6.02214076\times {{10} ^ {23}}$,
Zinc is a chemical element with the symbol Zn and atomic number 30. Zinc is a slightly brittle metal at room temperature and has a blue-silvery appearance when oxidation is removed. It is the first element in group 12 of the periodic table.
Now, for finding the number of moles associated with 23.3g of zinc,
So, we can use the formula: $n=\dfrac{m}{M}$,
Where, n is the number of moles, m is the given mass, and M is the molar mass of zinc,
We know the molar mass of zinc is 65,
So, putting the values we would get: $n=\dfrac {23.5}{65}$,
Simplifying it further we would get: $n=0.36moles$,
So, the number of moles for 23.3 g zinc comes out to be: 0.36 moles

Therefore, we can conclude that option (B) is correct.

Note: A mole of any substance or a particle is equal to the Avogadro's number which is equal to $\text{6}\text{.022 }\times \text{ 1}{{\text{0}}^{23}}$ particles such as electrons, proton, atom, etc. The mole is very important for calculating the large quantities. It is also advised to remember the atomic masses of the first 30 elements of the periodic table.