Question

a) Calculate the number of molecules in 111 g of CaCl2

b) What is the molar volume of CaCl2 at STP

c) What will be the number of atom in it?​

Answer 1

Explanation:

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A)

$\tt{Molecular ~weight~ of~ CaCl _{2} =111g/mol }$

$\tt{Ions~ in ~one ~calcium~ chloride ~molecule = Ca +² +2Cl = 3 ions }$

Now no. of molecules in 111g/mol of CaCl 2 = Avogadro's number

$\tt{= 6.02×10²³}$

$\tt{So~ number ~of ~ions ~in ~111g/mol ~of ~CaCl _{2} }$

$\tt{3×6.02×10^{23}ions = 3moles }</strong></p><p><strong>[tex] \tt{3×6.02×10^{23}ions = 3moles }$

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B)

At standard Temperature and Pressure (STP) the molar volume (Vm) is the volume occupied by one mole of a chemical element or a chemical compound. It can be calculated by dividing the molar mass (M) by mass density (ρ). Molar gas volume is one mole of any gas at a specific temperature and pressure has a fixed volume

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C)

The equation is fairly simple. The number of atoms of ANY substance in a volume is: # of atoms = N * (density) * volume / (Molecular Weight). N is a constant called Avogadro's number and its equal to 6.022*10²³ atoms/mole.

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Answer 2

Answer:

a) Use the formula;  $n = \frac{m}{Mr}$

   Where n is the number of moles, m is the mass, and Mr is the molar mass

   Molar mass of $CaCl_{2}$ = Mass of atom x number of molecules of the atom

                                      = 40(1) + 35.5(2)

                                      = 40 + 71

                                      = 111 g/mol

Number of moles,

                     $n = \frac{111}{111} \\\\n = 1$

Using the formula  $n = \frac{N}{L}$

Where n = Number of moles, N = number of molecules, L = Avogadro's constant

               $N = nL\\\\ N = 1 (6.02 \times 10^{23})\\\\ N = 6.02 \times 10^{23}$

Hence, there are $6.02 \times 10^{23}$ molecules in 111g of $CaCl_2$.