The correct answer is B. on Apex!
<u>Given:</u>
Mass of pure iron (Fe) = 3.4 g
<u>To determine:</u>
Mass of HBr needed to dissolve the above iron
<u>Explanation:</u>
Reaction between HBr and Fe is
Fe + 2HBr → FeBr₂ + H₂
Based on the reaction stoichiometry-
1 mole of Fe reacts with 2 moles of HBr
# moles of Fe = mass of Fe/atomic mass of Fe = 3.4/56 g.mol⁻¹ = 0.0607 moles
Therefore # moles of HBr = 2*0.0607 = 0.1214 moles
Molar mass of HBr = 81 g/mole
Mass of HBr = 0.1214 moles * 81 g/mole = 9.83 g
Ans: Mass of HBR required is 9.83 g
X ml - <span>25% alcohol mixture
y ml - </span><span>90% alcohol mixture
x+y = 455
0.25x ml alcohol in </span>x ml of 25% alcohol mixture
0.9y ml alcohol in y ml of 90% alcohol mixture
0.75*455= 341.25 ml alcohol in 455 ml of 75% alcohol mixture
0.25x+0.9y=341.25
System of equations:
x+y = 455 /*(-0.25) ------> -0.25x-0.25y = -0.25*455
0.25x+0.9y=341.25
-0.25x-0.25y=-113.75
0.25x+0.9y=341.25 Add both equations
0.25x+0.9y-0.25x-0.25y=341.25-113.75
0.65y =227.5
y=227.5/0.65 = 350 ml of 90% alcohol mixture
x+y=455
x+355=455
x=100 ml of 25% alcohol mixture
