Q1 / 170 · Manipal (MET) 2015 · Chemistry

How many moles of $\mathrm{Al}_2\left(\mathrm{SO}_4\right)_3$ would be in 50 g of the substance?

  • A
    0.0843 mol
  • B
    0.952 mol
  • C
    0.481 mol
  • Correct answer
    D
    0.140 mol

Solution

$\text { Number of moles }=\frac{\text { Mass }}{\text { Molecular mass }}$
Given, mass of $\mathrm{Al}_2\left(\mathrm{SO}_4\right)_3=50 \mathrm{~g}$ Molecular mass of $\begin{aligned} & \mathrm{Al}_2\left(\mathrm{SO}_4\right)_3=2 \times 27+3(32+4 \times 16)=342 \mathrm{~g} \\ & \therefore \text { moles of } \mathrm{Al}_2\left(\mathrm{SO}_4\right)_3=\frac{50}{342}=0.14 \mathrm{~mol} \end{aligned}$

Hence, the correct answer is option: 'D'.

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