Question

How many moles are present in a $34g$ sample of Iron $(Fe)$metal?

Answer 1

Hint:The question is based on the concept of number of moles and Molar Mass of compound/element. One mole of any compound contains mass equal to its molar mass. In this question we are asked to find out the number of moles in $34g$of glucose.
We know that number of moles in any compound is given by the formula mentioned below,
Number of moles = $\dfrac{given\,mass}{Molar\,mass}$
We will use the above formula to calculate the number of moles in $34g$of glucose molecules.
For this we should know the molar mass of iron. Once the molar mass is known it can be divided by the given mass in order to give the number of moles as stated in the above formula.

Complete answer:
Molar Mass of Iron $(Fe)\,=\,55.845gmo{{l}^{-1}}$
Given mass of Iron $(Fe)$ = $34g$
Using the Formula $number\,of\,moles=\,\,\dfrac{given\,mass}{molar\,mass}$we get
$number\,of\,moles\,=\,\,\dfrac{34}{55.845}$ = $0.6088\,moles$of Iron.
Hence the number of moles present in $34g$ of glucose is $0.609$ approximately.

Note:The questions based on moles concept are often misunderstood by many. Always be careful about the SI units of molar mass and various quantities mentioned in the question. Determine your starting point and ending point to determine the number of corresponding steps that will be necessary. Always be careful in calculating the molar mass of compounds as a slight mistake can make the entire question wrong. Always keep the molar masses of basic elements like carbon hydrogen, iron in tips. Whenever the answer comes out in decimal always use the rules of significant figures to round your answer to the proper nearest value possible.