Question

How many moles of $ Cu $ are in $ 10.00g $ of $ Cu $ ?

Answer 1

Hint: We know that the one mole is defined as the amount of substance that contains Avogadro’s number $ \left( {{N}_{0}} \right) $ of particles i.e. $ 6.022\times {{10}^{23}} $ particles. The molar mass of $ Cu $ is $ 63.55u $ , thus one mole of $ Cu $ weighs $ 63.55g $ and has $ 6.022\times {{10}^{23}} $ number of copper atoms in it.

Complete answer:
Copper belongs to $ {{11}^{th}} $ group and $ {{4}^{th}} $ period of the periodic table and is one of the Transition metal elements that lie in the d-block of the periodic table. Knowing the weight of the sample and it’s molecular mass we can not only know the number of moles but also the number of atoms present in the sample. Thus knowing the mass of sample provided and the molar mass we can easily calculate the number of moles of Copper present in our given sample.

From the information provided in the question we know that the provided sample has $ 10.00g $ Copper metal, We also know that the molecular mass of copper is $ 63.55u $ thus the mass of one mole of Cu is equal to $ 63.55g $ .
So, knowing the molar mass we can say that,
 $ 1g $ Of copper sample has $ \dfrac{1}{63.55} $ moles of Copper,
Thus, $ 10g $ of copper has $ \dfrac{10}{63.55} $ moles of copper or, $ 0.1574 $ moles of copper.

So, $ 10g $ of copper has $ 0.1574 $ moles of Copper.

Note: Note that the quite common mistake done by students is when they don’t observe the units of mass of sample provided because in certain questions the mass is given in$mg,\mu g,kg$etc., thus leading to an overall large error in value.