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11. An iron (Fe) wire with 5.00 cm in length was dropped into 350 0ml.2 375 M HC

ID: 104999 • Letter: 1

Question

11. An iron (Fe) wire with 5.00 cm in length was dropped into 350 0ml.2 375 M HCstion Afther the iw reacted completely with HC10, to produce ironl) perchlorate and hydrogn gas ( the soltion was titeated fot the remaining HCIO, by NaOH solution 258.9 ml, of 0 8413 M NaOit solution was needed fo itration (a) (2 points) What is the reaction equation between Fe ad C1 (b) (1 point) What is the reaction equation between HCIO, and NaOHl (c) (1 point) What is the net ionic reaction equation between HCIO, and Naon (d) (11 points) If you consider the iron wire as a cylinde of iron is 7.87 g/cm The arca of a circle with r as radius is r, what is the radius in inm of ron wire. The denity

Explanation / Answer

a) 2 HClO4 + Fe ===== H2 + Fe(ClO4)2 The iron II percholate is Fe(ClO4)2 with this we only need to balance the HClO4, just multiply it by 2

b) remember that an acid and a base produces a salt plus water so

NaOH + HClO4 ======= NaClO4 + H2O (l)

c) Overall reaction:

For this you have to split the molecules into ions like:

Na+ + OH- + H+ + ClO4- ====== Na+ + ClO4- + H2O , the water does not split into ion,

now we must remove the ions that appear on both sides (these are called expectator ions)

OH- + H+ ========= H2O net ionic equation

d) For this part we must calculate the mass that reacted with the HClO4, we must analyze the info

originally you have a solution of 2.375 M and 850 ml of it so apply:

Molarity = moles / volume

moles = Molarity * volume = 2.375 * 0.85 = 2.01875 moles

moles that didnt react with Fe and were neutralized with NaOH

0.8416 M * 0.2589 L =  0.218 moles of NaOH added, since it is a 1:1 reaction then we had 0.218 moles of HClO4 that didnt react with Fe so

moles that reacted with Fe = 2.01875 - 0.218 = 1.8 moles of HClO4 that reacted with Fe so according to our first equation 2 moles of acid needs 1 mole of Fe so you originally had

1.8 * 2 = 3.6 moles of Fe, Fe has a molar mass of 55.8 g/gmol then

mass = moles * molar mass

mass of Fe = 3.6 * 55.8 = 167.4 grams of Fe

density = mass / volume

volumes = mass / density = 167.4 / 7.87 (gr/cm3) = 21.27 cm3

For a cylinder we know that volume is lenght * Area of the base

since lenght is 5 cm then

21.27 / 5 = 4.254 cm2 this is the area of the base

since tha base is a circle

4.254 = 3.1416 * r2

r2 = 4.254 / 3.1416 = 1.354

r = 1.163 cm

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