What mass of hbr (in g) would you need to dissolve a 2.7 −g pure iron bar on a padlock?

The amount of HBr required to dissolve a given amount of pure iron bar is 7.76 grams.

Explanation:

To calculate the number of moles, we use the equation:

     .....(1)

Given mass of iron = 2.7 g

Molar mass of iron = 55.84 g/mol

Putting values in equation 1, we get:

The chemical equation for the reaction of HBr and pure iron follows:

By Stoichiometry of the reaction:

1 mole of iron metal reacts with 2 moles of HBr

So, 0.048 moles of iron metal will react with = of HBr

Now, calculating the mass of HBr by using equation 1, we get:

Molar mass of HBr = 80.91 g/mol

Moles of HBr = 0.096 moles

Putting values in equation 1, we get:

Hence, the amount of HBr required to dissolve a given amount of pure iron bar is 7.76 grams.