need help with number 1 part a and b PRELAB PROBLEMS EXPERIMENT UTA-549 Section

Question

need help with number 1 part a and b

PRELAB PROBLEMS EXPERIMENT UTA-549 Section 1. Use the half eeactions in Table to construct a fully balanced redov reaction between (show your half reactions): A: (NH Fe(soi 6H20 and KMno4 under acidic conditions B. Kvex, and KMno. under acidic conditions 2 Determine the mass percent K1CX, in a sample Unknown X. given the following infruation A sample of 1.25 g Unknownx was dissolved in mLDI water and 2s mL3M Hasoi. The sample was titrated with 0.0421 M KMno solution and it took 13.52 mLto reach the endpoint.

Explanation / Answer

2 KMnO4 + 8 H2SO4 + 10 (NH4)2Fe(SO4)2*6H2O = 2 MnSO4 + 5 Fe2(SO4)3 + K2SO4 + 10 (NH4)2SO4 + 68 H2O

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KMnO4 + 2 H2SO4 + K2C2O4 = 2 CO2 + 2 KSO4 + KMnO2 + 2 H2O

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Fe^2+ Fe^3+
MnO4^- Mn^2+

Balance these reactions

. Balance O by adding H2O, H by adding H^+, charge by adding electrons to the more positive side. Then add them so that the electrons cancel.

Fe^2+ Fe^3+
Fe^2+ Fe^3+ + e^-

MnO4^- Mn^2+
MnO4^- Mn^2+ + 4H2O
MnO4^- + 8H^+ Mn^2+ + 4H2O
MnO4^- + 8H^+ + 5e^- Mn^2+ + 4H2O

5 times the Fe equation and 1 times the Mn equation to get 5 electrons on both sides of the arrow.

MnO4^- + 8H^+ + 5e^- Mn^2+ + 4H2O
5Fe^2+ 5Fe^3+ + 5e^-
——————————————————
MnO4^- + 5Fe^2+ + 8H^+ Mn^2+ + 5Fe^3+ + 4H2O (net ionic equation)

KMnO4 + 5(NH4)2Fe(SO4)2·6H2O + 4H2SO4 Mn^2+ + 5Fe^3+ + 4H2O + K^+ + 10NH4^+ + 14SO4^2- + 6H2O (add in the remaining ions)

KMnO4 + 5(NH4)2Fe(SO4)2·6H2O + 4H2SO4 MnSO4 + 2.5Fe2(SO4)3 + 10H2O + 0.5K2SO4 + 5(NH4)2SO4 (combine ions as necessary)

2KMnO4(aq) + 10(NH4)2Fe(SO4)2·6H2O(aq) + 8H2SO4(aq) 2MnSO4(aq) + 5Fe2(SO4)3(aq) + K2SO4(aq) + 10(NH4)2SO4(aq) + 20H2O(l) (eliminate decimals and add states for full equation)

For the second reaction, C2O4^2- is oxidised to CO2.

The MnO4^- reaction is the same as above.

C2O4^2- CO2
C2O4^2- 2CO2 + 2e^-

Take the Mn equation times 2 and the C equation times 5, then work as before.

2MnO4^- + 16H^+ + 10e^- 2Mn^2+ + 8H2O
5C2O4^2- 10CO2 + 10e^-
—————————————————————
2MnO4^- + 5C2O4^2- + 16H^+ 2Mn^2+ + 10CO2 + 8H2O (net ionic equation)
2KMnO4 + 5K2C2O4 + 8H2SO4 2Mn^2+ + 10CO2 + 8H2O + 12K^+ + 8SO4^2-
2KMnO4(aq) + 5K2C2O4(aq) + 8H2SO4(aq) 2MnSO4(aq) + 10CO2(g) + 8H2O(l) + 6K2SO4(aq) (full equation)

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