Question

How many formula units make up 30.4 g of magnesium chloride (mgcl2)?

Answer 1

Answer: The number of formula units in the given amount of magnesium chloride is $1.93\times 10^{23}$

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 magnesium chloride = 30.4 g

Molar mass of magnesium chloride = 95.2 g/mol

Putting values in above equation, we get:

$\text{Moles of magnesium chloride}=\frac{30.4g}{95.2g/mol}=0.32mol$

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 $6.022\times 10^{23}$

We are given:

Number of moles of magnesium chloride = 0.32 moles

Number of formula units = $0.32\times 6.022\times 10^{23}=1.93\times 10^{23}$

Hence, the number of formula units in the given amount of magnesium chloride is $1.93\times 10^{23}$

Answer 2

There are 1.923×10^23 formula units in 30.4g mgcl2

molar mass of mgcl2= 95.211g/mol
magnesium= 24.305g/mol
chlorine= 35.45g/mol times 2
24.305+(35.45*2)= 95.211g/mol

sample divided by molar mass times Avogadro's number gives u the formula units

30.4÷ 95.211= .31929
.3193*6.022=1.9288