Question

What minimum volume of 14.0 M hydrochloric acid would be required to completely dissolve a 600.0 −g iron bar?

I'm getting around 2.3 L but it's saying it's incorrect...

Answer 1

hope this helps

1 OH- plus H+ = HOH or H2O One mole of OH- combines with one mole of H+ to make one mole of water. therefore .50 moles of OH- will combine with .50 moles of H+ to make .50 moles of H2O and the solution will be neutral with a pH of 7.

2. Balance the equation first. 2 HCl + Mg = MgCl2 plus H2(g)

Now get the l0 grams of Mg into moles. l0 grams Mg over 24 grams Mg/mole = .417 moles Mg

Now notice in the balanced equation that 2 moles of HCl reacts with one mole of Mg, therefore we need two times as many moles of HCl as we have of Mg.

2 times .417 moles Mg = .833 moles HCl needed

In any solution Moles solute = Molarity times volume in LITERS

switching this around Volume in Liters = Moles solute over Molarity

Volume HCl needed = .833 moles HCl over 7.0 Molar HCl = .119 Liters or 119 ml

3. Reaction balanced 2 Fe + 6HCl = 2 FeCl3 + 3 H2

Get the 450 grams of iron into moles first. 450 gms Fe over 56 grams Fe per mole = 8.04 moles Fe

Now use the balanced equation as a math platform. Write out the equation on a ;piece of paper.

Over the 2Fe enter 8.04 moles and below the same enter its coefficient of 2 moles

Now over the 6HCl enter X moles and below the same enter its coefficient of 6

Now cross multiply through the equation and solve for X moles of HCl I got 24.1 moles of HCl needed.

Moles HCl = Molarity times Volume in Liters

Volume in liters = Moles HCl over Molarity which = 24.1 moles HCl over 14.0 Molar HCl acid
which = 1.72 Liters HCl acid or 1720 ml. If if the pen held 5 ml of acid, it would have to be refilled about 344 times. No way this would fit into the pen.

Answer 2

The work done by Nick is interesting but it doesn't answer the question.
Fe + 2HCl ==> FeCl2 + H2

mols Fe = grams/molar mass = ?
Using the coefficients in the balanced equation, convert mols Fe to mols HCl. That's mols HCl = twice mols Fe.

Now convert mols HCl to volume.
M HCl = mols HCl/L HCl.
You know M HCl and mols HCl, solve for L HCl. Convert to mL if desired. 2.3 L is way too large by a factor like 2000 time too large.