1How many milligrams of water are produced when 300 millimeters 0.2M sulfuric ac

Question

1How many milligrams of water are produced when 300 millimeters 0.2M sulfuric acid are mixed with one gallon of 0.002 M Calcium hydroxide .The reaction took place with 25% of efficiency. The reaction products are water and Calcium sulfate.

2Why are atomic weights relative weights?

3 How many grams of Fe were required if a reaction of Iron and enough HCl produced 0.42lbs. of FeCl2. The reaction took place with 37% of efficiency. The equation is not balanced.1kg = 2.2lbs

Fe(s) + HCl (aq) CaCl2 (aq) + H2 (g)

Explanation / Answer

NOTE that 300 milimeters are probably mililiters so...

V = 300 ml

M = 0.2 M of H2SO4

V = 1 gal or 3.79 l

M = 0.002 M of Ca(OH)2

25% conversion

H2SO4 + Ca(OH)2 ---> 2H2O + CaSO4(aq)

calculate moles of H2O produced:

mol of acid = 300*.2 = 60 mmol of acid

mol of base = 3.79*.02*1000 = 75.8 mmol of base

ratio is 1:1 so acid is limiting reactant

60 mmol of acid react to form 2*60 mmol of h2o; 120 mmol of water will be produced

120 mmol --> 0.12 mol ofH2O

But on ly 25% is actually produced so 0.12*0.25 = 0.03

MW of H2O = 18

mass = mol*MW = 0.03*18 = 0.54 grams of H2O, if you need mg, x1000, 540 mg of H2O produced

2Why are atomic weights relative weights?

they are relative since they are related to their mole:mass ratio i.e.

if you have Carbon MW = 12

this mean this is 12 grams per gmol, 12 lb per lbmol, 12 kg per kmol, etc...

They are related to their ratios

3)

Fe(s) + 2HCl (aq) FeCl2 (aq) + H2 (g)

m = Fe is

mass of FeCl2 = 0.42 lb or 0.191 kg or 191 grams of FeCl2 are produced

n = 37%

Note that if we porduced only 37% then

191 grams, fi reacted completely, should be 191/0.37 = 516.2 grams in total

do the balance based on that

MW of FeCl2 = 126.751g/mol

mol in 516.2 grams --> 516.2/126.751 = 4.07 mol of FeCl2 produced

since ratio is 1:1 (1 mol of Fe to produce 1 mol of FeCl2)

then, we had 4.07 mol of FE,

MW of Fe = 55 g/mol

mass = mol*MW = 4.07*55 = 223.85 grams of Fe are needed

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