The number of gold atom : 1.204 x 10²¹
Given
0.6 g of 18 carat gold
mass number of gold = 197
24 carat as 100% gold
Required
The number of gold atom
Solution
Percentage of gold in 18 carat :
[tex]\tt \dfrac{18}{24}\times 100\%=75\%[/tex]
Mass of gold in 0.6 g of 18 carat :
[tex]\tt 75\%\times 0.6~g=0.45~g[/tex]
mol :
[tex]\tt mol=\dfrac{mass}{MW}=\dfrac{0.45}{197}=0.0023[/tex]
A mole is a number of particles(atoms, molecules, ions) in a substance
1 mole = 6.02.10²³ particles
So the number of gold atom :
[tex]\tt 0.0023\times 6.02\times 10^{23}=1.204\times 10^{21}[/tex]
