Question

a) 200.0 g of Ca(C₂H₃O₂)₂ was found in the chemistry laboratory. 

      Calculate

          i. the molecular mass of 1 mole Ca(C₂H₃O₂) _2.

         ii.  the number of  moles of Ca(C₂H₃O₂)₂  that exists   

        iii.  the number of Ca(C₂H₃O₂)₂ molecules present

Answer 1

i.) Molecular mass of$Ca(C_2H_3O_2)_2$

$=40+(12.0102*2+1.00794*3+15.9994*2)2\newline =158.166g/mol$

ii.) No. of moles$=\dfrac{mass}{molar mass}$

$Moles=\dfrac{200}{158.166}$

$=1.2645mol$

iii.) Number of molecules present.

Avogadro's number=$6.0221*10^{23}$ molecules per mole.

$1mol=6.0221*10^{23}\newline 1.2645=??$

$=1.2645×6.0221*10^{ 23}\newline =7.6149*10^{23} molecules$