6. What volume of 6M Ba(OH)2 will be needed to neutralize 400.0 ml of a 2.0 M HCl solution?

133 mL

Explanation:

M= mol solute/ L solution

mol solute= M *L solution

mol solute = (2.0 M * 0.4 L)

mol solute= 0.8 mol HCl= mol H

We need the same amount of  OH moles to neutralize the solution

L solution = mol solute/M

L solution= 0.8 mol Ba(OH)2/ 6M

L solution=0.133 L=133 mL

first, consult an activity series chart to determine if al is more reactive than fe. it is, so it will replace the fe. now, one can continue with the problem.

next, make sure you have a correctly balanced equation.

3feo + 2al ==> 3fe + al2o3

now, determine which reactant (feo or al) is in limiting supply.

moles feo present = 125 g x 1 mole/71.8 g = 1.74 moles

moles al present = 25.0 g x 1 mole/26.98 g = 0.927 moles

since from the balanced equation, it take 3 mol feo for every 2 mol al, al will be limiting.

you can determine this simply by dividing moles of each by their coefficient in the balanced equation. for example: 1.74/3 = 0.58 and 0.927/2 = 0.464. al is less, so it is limiting.

finally, using the stoichiometry in the balanced eq. determine mass of fe that can be produced from 0.927 moles of al.

0.927 moles al x 3 moles fe/2 moles al x 55.8 g/mole = 77.6 g