A certain mass(m) of an impure iron sample of 40% purity ,is treated with an excess of HCl to give H2 that occupies 44.8 L at s.t.p ( Vm=22.4) where the yeild of the reaction is 0.8.
A) calculate m.
B) deduce the mass of HCl reacted.
Thanks in advance!!
See the response by Bob Pursley above.
To solve this problem, we first need to understand the given information and the chemical equation involved.
The impure iron sample is being treated with an excess of HCl, which produces hydrogen gas (H2) as one of the products. We are given that the impure iron sample has a purity of 40%.
Let's proceed with solving the problem step by step:
A) Calculate the mass (m) of the impure iron sample:
The mass of the impure iron sample can be calculated by using the equation:
m = (mass of pure iron / purity) * 100
Given that the purity of the iron sample is 40%, we can rewrite the equation as:
m = (mass of pure iron / 0.4)
We need to find the mass of pure iron to calculate m. To do that, we use the volume of hydrogen gas produced.
B) Deduce the mass of HCl reacted:
The balanced chemical equation for the reaction between iron (Fe) and hydrochloric acid (HCl) is:
Fe + 2HCl -> FeCl2 + H2
From the balanced equation, we can see that 1 mole of iron reacts with 2 moles of HCl to produce 1 mole of hydrogen gas. So, the ratio of moles of HCl to moles of hydrogen is 2:1.
We are given that the volume of hydrogen gas produced at standard temperature and pressure (STP) is 44.8 L. We also know that the volume of 1 mole of any gas at STP is 22.4 L. Therefore, the number of moles of hydrogen gas produced can be calculated as:
moles of H2 = volume of H2 / volume of 1 mole of H2
= 44.8 L / 22.4 L/mol = 2 mol
Since the yield of the reaction is given as 0.8, we need to adjust the moles of hydrogen gas produced accordingly:
moles of H2 (adjusted) = moles of H2 * yield
= 2 mol * 0.8 = 1.6 mol
Now, back to calculating the mass of HCl reacted. As mentioned earlier, the ratio of moles of HCl to moles of hydrogen is 2:1. Therefore, the number of moles of HCl reacted is half the number of moles of hydrogen gas produced:
moles of HCl = moles of H2 (adjusted) / 2
= 1.6 mol / 2 = 0.8 mol
To calculate the mass of HCl, we need to know its molar mass. The molar mass of HCl is approximately 36.5 g/mol. Therefore, the mass of HCl reacted can be calculated as:
mass of HCl = moles of HCl * molar mass of HCl
= 0.8 mol * 36.5 g/mol = 29.2 g
Now, we have obtained the mass of HCl reacted. We can use this information to calculate the mass (m) of the impure iron sample.
m = (mass of pure iron / 0.4)
Given that the purity of the iron sample is 40%, we can rewrite the equation as:
m = (mass of pure iron / 0.4)
We need to find the mass of pure iron to calculate m. To do that, we use the volume of hydrogen gas produced.
To summarize:
A) The calculated mass (m) of the impure iron sample is:
m = (mass of pure iron / 0.4)
B) The calculated mass of HCl reacted is:
mass of HCl = 29.2 g
Please note that the molar masses and the yield of the reaction are used for illustrative purposes and may vary depending on actual values.