1) If 2.566 g of Iron (II) chloride was dissolved in water and the final volume
ID: 575087 • Letter: 1
Question
1) If 2.566 g of Iron (II) chloride was dissolved in water and the final volume of solution was 250.00 mL, what is the molarity of total ions?
2) If 2.317 g of Iron (III) bromide is transferred to a volumetric flask, what is the molarity (M), if the volume of solution is 250 ml?
3)Using the mass percent of iron in iron (III) chloride, calculate the number of moles of iron in 128.546g of FeCl3. ( The Molar mass of iron is 55.85 grams.)
4) If 25.00 mL of 0.45381 M solution is diluted to a new volume of 100.00 mL, what is the new concentration of the solution?
5) Calculate the mole fraction of Fe when iron(III) chloride hexahydrate is dissolved into 128.384 deionized water. ( The molar mass for water is 18.00 grams and for iron is 55.85 grams.)
Please show work
Explanation / Answer
1) No of mole = mass/molar mass
mass of FeCl2 = 2.566g
molar mass of FeCl2 = 126.75g/mol
No of mole of FeCl2 = 2.566g/126.75g/mol =0.02024mol
Molarity = No of mole of solute in 1liter(1000ml) of solution
Molarity of FeCl3 =( 0.02024mol/250ml)×1000ml = 0.08096M
Molarity of Fe3+ = 0.08096M
Molarity of Cl- = 2×0.08096M = 0.16192M
Molarity of total ions =0.08096M + 0.16192M =0.2429M
2) mass of FeBr3 = 2.317g
molar mass of FeBr3 = 295.56g/mol
No of mole of FeBr3 = 2.317g/295.56g/mol =0.007839mole
Volume of solution = 250ml
Molarity of FeBr3 = (0.007839mol/250ml)×1000ml =0.031356M
3)
Molar mass of FeCl3 = 162.20g/mol
Molar mass of Fe = 55.85g/mol
No of Fe in FeCl3 = 1
Mass % of Fe in FeCl3 = (55.85g/162.2g)×100= 34.433%
mass of FeCl3 = 128.546g
mass of Fe in 128.546g of FeCl3 = (34.433/100)×128.546g = 44.262g
No of mole of Fe = 44.262g/55.85g/mol = 0.79252
4)
C1×V1 = C2×V2
C2 = C1×V1/V2
C2 = 0.45381M × 25ml/100ml = 0.11345M
New concentration of the solution = 0.11345M
5)
Mole fraction = No of mole /total mole
No of mole of Fe = 0.79252 (as calculated in 3)
No of mole of H2O = 128.384g/18g/mol =7.13244
Total mole = 7. 92496
mole frection of Fe = 0.79252/7.92496 = 0.1000
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