Calculate the number of gold atoms present in 0.450 g of a gold ring made from 22 Carat Gold given that the atomic mass of a gold is 197 and pure gold is 24 carets
Answers
Answer:
The number of gold atoms in 300mg of a gold ring of 20 -carat gold ( Au=197
: pure gold is 24 carat) are:
Answer
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Hint: 1 Carat gold is equal to 0.2 gram gold. Therefore 20 carat gold equals 4 grams. And 24 carats is said to be pure gold.
Formula used: 1mole = atomic weight =6.023×1023
no. of atoms
Complete step by step answer:
If 24 carats is pure gold then if the number of atoms in 24 carats is calculated then calculation of no. of atoms of 20 carat will be easy.
Now at first, according to the mole concept we know 1 mole of any substance is equal to its molecular weight. And 1 mole is also equal to the Avogadro’s number of atoms i.e. 6.023×1023
.
Therefore, 1mole = atomic weight =6.023×1023
no. of atoms
According to this it can be said that 197 gm pure gold contains =6.023×1023
number of atoms.
Now according to the question 24 carat is pure gold. Therefore, it can be said that,
197 gm 24-carat gold contains =6.023×1023
number of atoms.
300mg is equal to 3001000=0.3grm
.
Now,0.3 grams 24-carat gold contains 6.023×1023×0.3197
number of atoms
So, 0.3 grams of 24-carat gold contains 9.172×1020
number of atoms.
Therefore, 0.3 grams 20-carat gold contains 9.172×1020×2024
number of atoms.
Which is equal to 7.643×1020
number of atoms .
So , 0.3 grams of 20-carat gold contains 7.643×1020
number of atoms.
Note:
1mole = atomic weight =6.023×1023
no. of atoms. The formula of equivalent weight is,
Equivalentweight=Molecularweightnumberofequivalentmoles
.
For acids the number of equivalents is equal to the number of H+
present in one molecule. And for bases the number of HO−
groups present in one molecule. The equivalent weight of any substance cannot be greater than its molecular weight. Either the value of equivalent weight is equal or less than the molecular weight of that substance.