Question

The mass of a quantity of NiCl2

is 24.6 g. How many formula units are in the sample?
A. 1.1 3 1023 NiCl2
formula units
B. 1.9 3 1027 NiCl2
formula units
C. 3.2 3 1023 NiCl2
formula units
D. 5.3 3 10–21 NiCl2
formula units

Answer 1

Not sure, is it :
B.
1.9 3 1027 NiCl2
formula units

Answer 2

Answer: The correct answer is Option A.

Step-by-step explanation:

To calculate the number of moles, we use the equation:

`\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}`

Given mass of nickel chloride = 24.6 g

Molar mass of nickel chloride = 129.6 g/mol

Putting values in above equation, we get:

`\text{Moles of }NiCl_2=(24.6g)/(129.6g/mol)=0.19mol`

Formula units is defined as lowest whole number ratio of ions in an ionic compound. It is calculate by multiplying the number of moles by Avogadro's number which is
`6.022* 10^(23)`

We are given:

Number of moles of nickel chloride = 0.19 moles

Number of formula units =
`0.19* 6.022* 10^(23)=1.1* 10^(23)`

Hence, the correct answer is Option A.