Question

What minimum mass of HCl{\rm HCl} in grams would you need to dissolve a 2.2g{\rm g} iron bar on a padlock?

Answer 1

Answer on Question #44156 - Chemistry - Physical Chemistry

Question:

What minimum mass of HCl{\rm HCl} in grams would you need to dissolve a 2.2g{\rm g} iron bar on a padlock?

Solution:

$$\mathrm{Fe} + 2 \mathrm{HCl} \rightarrow \mathrm{FeCl_2} + \mathrm{H_2} \uparrow$$ $$n(\mathrm{Fe}) = \frac{m(\mathrm{Fe})}{M(\mathrm{Fe})} = \frac{2.2\,g}{56\,g/mole} = 0.039\,mole$$

M (Fe) - Formula mass

$$n(\mathrm{HCl}) = 2n(\mathrm{Fe}) = 2 \cdot 0.039\,mole = 0.078\,mole$$ $$m(\mathrm{HCl}) = n(\mathrm{HCl}) \cdot M(\mathrm{HCl}) = 0.078 \cdot 36.6\,g/mole = 2.8\,g.$$

Answer: 2.8 g.

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