Problem: Iodine is present in Chilean saltpeter as iodate anion (IO3-). The amount of iodate anion in a particular sample may be determined by dissolving the sample and then reacting the IO3-(aq) with excess aqueous sodium bisulfite (NaHSO3(aq)) via: 2 IO3-(aq) + NaHSO3 (aq) -----> I2(aq) + Na+(aq) + 5SO4-2(aq) + H+(aq) + H2O(l) . (1)
The I2(aq) produced above is then reacted with (excess) aqueous potassium iodide (KI(aq)):
KI(aq) + I2(aq) -----> K+(aq) + I3-(aq) . (2)
The I3−(aq) is then reacted completely with a stoichiometric amount of aqueous
sodium thiosulfate, Na2S2O3 (aq):
2 Na2S2O3(aq) + I3-(aq) -----> Na+(aq) + I-(aq) + S4O6-2(aq) . (3)
First, write out and balance each of the partially balanced reactions (1, 2, & 3) above.
Suppose a 80.680 g sample of Chilean saltpeter produces sufficient I2(aq) to react completely with 5.128 g of Na2S2O3 . Calculate the mass percent of iodate anion, IO3- , in the saltpeter sample.
*If you can't read the charges, I have attached the Word document of the problem.
*Please show all steps and calculations
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Energy, q, w, Enthalpy, and Stoichiometry II and Specific Heat
Problem 1 - Energy, q, w, Enthalpy, and Stoichiometry
Consider the following reaction:
2Mg(s)+O2(g)>>2MgO(s)ΔH = -1204kJ
1) Is this reaction exothermic or endothermic?
2) Calculate the amount of heat transferred when 2.1 g of Mg(s) reacts at constant pressure.
Express your answer using two significant figures.
3)How many grams of MgO are produced during an enthalpy change of -94.0 kJ ?
4)How many kilojoules of heat are absorbed when 7.80 g of MgO(s) is decomposed into Mg(s) and O2(g) at constant pressure?
Problem 2 - Specific Heat
The specific heat of iron metal is 0.450 J/g*K
How many J of heat are necessary to raise the temperature of a 1.10 - Kg block of iron from 26.0 Celsius degrees to 88.0 Celsius degrees?