Answer: The number of cations are
and number of anions are
in 6.42 g of KBr.
Explanation:
The molar mass of KBr is (39.10 + 79.90) g/mol = 119.00 g/mol
Now, the dissociation equation for KBr is as follows.
![KBr \rightarrow K^{+} + Br^{-}](https://tex.z-dn.net/?f=KBr%20%5Crightarrow%20K%5E%7B%2B%7D%20%2B%20Br%5E%7B-%7D)
This means that 1 mole of KBr is forming 1 mole of
(cation) and 1 mole of
(anion).
According to mole concept, 1 mole of every substance contains
atoms. Hence, number of cations present in 6.42 g KBr is calculated as follows.
![No. of cations = Moles \times 6.022 \times 10^{23}\\= \frac{mass}{molar mass} \times 6.022 \times 10^{23}\\= \frac{6.42 g}{119.00 g/mol} \times 6.022 \times 10^{23}\\= 3.24 \times 10^{22}](https://tex.z-dn.net/?f=No.%20of%20cations%20%3D%20Moles%20%5Ctimes%206.022%20%5Ctimes%2010%5E%7B23%7D%5C%5C%3D%20%5Cfrac%7Bmass%7D%7Bmolar%20mass%7D%20%5Ctimes%206.022%20%5Ctimes%2010%5E%7B23%7D%5C%5C%3D%20%5Cfrac%7B6.42%20g%7D%7B119.00%20g%2Fmol%7D%20%5Ctimes%206.022%20%5Ctimes%2010%5E%7B23%7D%5C%5C%3D%203.24%20%5Ctimes%2010%5E%7B22%7D)
As according to the equation, there are equal number of moles of both cation and anions.
This means that the number of anions are also
.
Thus, we can conclude that the number of cations are
and number of anions are
in 6.42 g of KBr.