If 7.02 g of potassium dichromate (294.185 g/mol) is used to prepare a solution and then...

If 7.02 g of potassium dichromate (294.185 g/mol) is used to prepare a solution and then reacted with 18.15 g of an iron (II) compound. What mass of iron(II) is present in the sample?

Expert Solution

Given data:

The mass of potassium dichromate (K₂Cr₂O₇) used = 7.02 g.

The molar mass of K₂Cr₂O₇ = 294.185 g/mol

Therefore, the no. of moles of K₂Cr₂O₇ = 7.02/294.185, i.e. 0.02386

The mass of iron (II) compound used in the reaction = 18.15 g.

The molar mass of iron = 55.845 g/mol

Therefore, the no. of moles of Fe(II) = 18.15/55.845, i.e. 0.325

According to the balanced equation for the reaction between K₂Cr₂O₇ and Fe(II), there will be 1 (K₂Cr₂O₇) : 6 (Fe(II))-mole ratio.

Reason: Cr(VI) reduces to Cr(III). Here 2 Cr(VI) are present, so they need 6 electrons, whereas, Fe(II) oxidizes to Fe(III). Hence 6 moles of Fe(II) is needed for 1 mole of Cr(VI)

Therefore, the no. of moles of iron(II) present in the sample = 0.325 - (6*.02386), i.e. 0.18184

Hence, the mass of iron(II) present in the sample = 0.18184*55.845, i.e. 10.15 g.

queen_honey_blossom answered 2 years ago

The heat of solution of potassium acetate (KC2H3O2) in water is -15.30 kJ/mol. If 19.70 g...

The heat of solution of potassium acetate (KC2H3O2) in water is -15.30 kJ/mol. If 19.70 g of KC2H3O2(s) is dissolved in 600.0 mL of water that is initially at 24.50 °C, What will be the final temperature (in degrees Celcius) of the resulting aqueous solution? (Assume no heat exchange with the surroundings.)

Potassium dichromate is used in breathalyzers to measure alcohol content. The balanced chemical equation for the...

Potassium dichromate is used in breathalyzers to measure alcohol content. The balanced chemical equation for the reaction between ethanol and potassium dichromate is given below. 3CH3CH2OH (aq) + 2K2Cr2O7 (aq) + 8H2SO4 (aq) --> 3CH3COOH (aq) + 2Cr2(SO4)3 (aq) + 2K2SO4 (aq) + 11H2O (l) a. what is the oxidation state of Cr is Kr2Cr2O7? b. what is the oxidation state of Cr in Cr2(SO4)3 c. Is Cr oxidized or reduced in the reaction? Explain.

Potassium dichromate (K2Cr2O7) is a bright orange salt that can be converted to a blue-violet solution...

Potassium dichromate (K2Cr2O7) is a bright orange salt that can be converted to a blue-violet solution of Cr3+ ions. Under certain conditions, K2Cr2O7 reacts with ethanol (C2H5OH) to produce carbon dioxide gas. The legal definition of intoxication is a blood alcohol (C2H5OH) level of 0.08% by mass or higher. In a given case, 35.48 mL of 0.05182 M K2Cr2O7 was required to titrate a 50.02 g sample of blood. From the tested sample, should the person be arrested for a...

An unknown Fe(II) sample is added to 2.50 mL of a 0.0300 M potassium dichromate solution...

An unknown Fe(II) sample is added to 2.50 mL of a 0.0300 M potassium dichromate solution (in acidic medium) in a 25 mL volumetric flask. 2 M H2SO4 is added to fill the flask to the calibration mark. After the reaction proceeds to completion, the absorbance of the solution at 447 nm is measured to be 0.550 using a 1.00-cm path length. Calculate the following and enter your answers with correct significant figures. Extinction coefficient of Cr2O72-in 2M sulfuric acid...

0.1200 g of potassium dichromate primary standard is dissolved, quantitatively transferred into a 250-mL volumetric flask...

0.1200 g of potassium dichromate primary standard is dissolved, quantitatively transferred into a 250-mL volumetric flask and diluted to volume. 0.3000 g an unknown iron ore sample was dissolved in hydrochloric acid, treated with stanous chloride and mercury(II) chloride, quantitatively transferred to a 100-mL volumetric flask and diluted to volume. 25.00 mL of the unknown iron(II) solution was pipetted into 500-mL Erlenmyer flask and titrated with the potassium dichromate solution. 28.00 mL of potassium dichromate is required to reach the...

Calculate the masses of NaCl (58.44 g/mol) and KCl (74.55 g/mol) that are required to prepare...

Calculate the masses of NaCl (58.44 g/mol) and KCl (74.55 g/mol) that are required to prepare 500.00 mL of a standard solution that contains N a + Na+ and K + K+ present at 540.0 ppm w/v. mass of NaCl ____ mass of KCl _____ please show work.

a). Calculate the molar mass in g/mol of the following compound (ammonium dichromate): (NH4)2Cr2O7 b). Calculate...

a). Calculate the molar mass in g/mol of the following compound (ammonium dichromate): (NH4)2Cr2O7 b). Calculate the mass, in g, of the following: 0.158 mol IF5 (iodine pentafluoride) c). Calculate the amount, in moles, of the following: 25.4 g Pb(C2H3O2)2 (lead (II) acetate) Professors Note: Make sure that you give your answer in a clear and well-reasoned manner, providing necessary explanation on how did you come up with it. d). Calculate the percent by mass of C, H, and O...

A solution is 5.66 % by mass NH3 (MM 17.04 g/mol) in water (MM 18.02 g/mol)....

A solution is 5.66 % by mass NH3 (MM 17.04 g/mol) in water (MM 18.02 g/mol). The density of the resulting solution is 0.974 g/mL. What is the mole fraction, molarity and molality of NH3 in the solution?

In the reaction of copper with potassium dichromate and sulfuric acid, the products are copper (1)...

In the reaction of copper with potassium dichromate and sulfuric acid, the products are copper (1) sulfate, potassium sulfate, water, and chromium(III) sulfate. First, write a balanced net ionic equation for this reaction. Then consider the reaction taking place with 100.0 grams of copper, 150.0 grams of potassium dichromate, and 400.0 grams of sulfuric acid. How many grams of potassium sulfate could be produced in this reaction?

A 50.0 g solution (density = 1.12 g/mL) of potassium fluoride is placed in an evaporating...

A 50.0 g solution (density = 1.12 g/mL) of potassium fluoride is placed in an evaporating dish and the solvent is evaporated, leaving 8.10 g of solid behind. Calculate the concentration of the solution in units of a) mass percentage b) molarity c) molality

Question