Sulfide in a water sample is coulometrically titrated with iodine (H2S + I2 ----> S + 2H+ + 2I-). If a 10.00 mL aliquot of the water sample requires a current of 0.75 A for 5.4 minutes to reach the end point, what is the molarity of the sulfide in the water sample?
(A) 0.5036 (B) 0.1259 (C) 0.0051 (D) 0.0013
In: Chemistry
A 0.1358-g portion of potassium iodate (MW 214.00), about 2 g of
potassium
iodide, and 2 mL of 6 M hydrochloric acid were dissolved in 25 mL
of distilled
water. The triiodide formed during the ensuring reaction was
titrated to the
starch end point with 31.94 mL of a thiosulfate solution. A
25.00-mL triiodide
sample solution was titrated to the end point with 21.33 mL of the
standardized
thiosulfate solution. Calculate the concentrations of the
thiosulfate solution and
the triiodide solution.
In: Chemistry
The density of liquid oxygen at its boiling point is 1.14 kg/L , and its heat of vaporization is 213 kJ/kg .
How much energy in joules would be absorbed by 2.0 L of liquid oxygen as it vaporized?
Express your answer to two significant figures and include the appropriate units.
Water's heat of fusion is 80. cal/g , and its specific heat is 1.0calg??C .
Some velomobile seats have been designed to hold ice packs inside their cushions. If you started a ride with ice packs that held 1400 g of frozen water at 0 ?C , and the temperature of the water at the end of the ride was 32 ?C , how many calories of heat energy were absorbed?
Express your answer to two significant figures and include the appropriate units.
Water's heat of fusion is 80. cal/g , its specific heat is 1.0calg??C, and its heat of vaporization is 540 cal/g .
A canister is filled with 390 g of ice and 100. g of liquid water, both at 0 ?C . The canister is placed in an oven until all the H2O has boiled off and the canister is empty. How much energy in calories was absorbed?
Express your answer to two significant figures and include the appropriate units.
In: Chemistry
For a particular redox reaction NO is oxidized to NO3– and Ag^+ is reduced to Ag. Complete and balance the equation for this reaction in basic solution. Phases are optional.
In: Chemistry
Consider the following reaction at constant P. Determine the value of ΔSsurroundings at 298 K? Predict whether or not this reaction will be spontaneous at this temperature. N2(g) + 2 O2(g) → 2 NO2(g); ΔH = +66.4 kJ
(Please show work and thank you for taking the time to answer.)
In: Chemistry
In: Chemistry
If calcium sulfate and barium sulfate do not form mixed crystals (i.e. they only form 1:1 species), what is the maximum fraction of the barium ion that can be precipitated as the sulfate from a solution that is initially 0.080 M in Ba2+ and 0.100 M in Ca2+, before the precipitation of calcium sulfate starts? For BaSO4, Ksp = 1.1 x 10-10, for CaSO4, Ksp = 2.4 x 10-5
In: Chemistry
Sanger's reagent, DNFB, is known to react with phenolic, imidazole, and free amino groups. With this in mind, would it be possible to determine the N and C terminals of a dipeptide composed of tyrosine and lysine?
In: Chemistry
Assume 200. mL of 0.400 M HCl is mixed with 200 mL of 0.250 M Ba(OH)2 in a constant-pressure calorimeter. The temperature of the solutions before mixing was 25.10C; after mixng and alowing the reaction to occur, the temperature is 27.78C. Determine ΔrH for this reaction in units of kJ/mol-rxn.
2 HCl(aq) + Ba(OH)2(aq) -> BaCl2(aq) + 2 H2O(l)
The densities of all solutions are 1.00 g/mL
The specific heat capacitites of all solutions are 4.20 J/(gC)
In: Chemistry
3) Gold-198 has a half-life of 2.7 days. How much of a 662.5 mg gold-198 sample will remain after 13.5 days?
In: Chemistry
Coal powered electricity has only about 30% total efficiency (i.e. from point of combustion to your home) – give a technical explanation of why this is so.
In: Chemistry
1) The pressure inside a hydrogen-filled container was 2.10 atm at 21 ∘C. What would the pressure be if the container was heated to 87 ∘C ?
2) At standard temperature and pressure (0 ∘C and 1.00 atm ), 1.00 mol of an ideal gas occupies a volume of 22.4 L. What volume would the same amount of gas occupy at the same pressure and 70 ∘C ?
In: Chemistry
The active ingredient in a zinc nutritional supplement is ZnSO4·7H2O (molar mass = 287.58 g/mol). Ten zinc tablets containing a mix of the active ingredient and an inactive filler were ground and mixed together thoroughly. The total mass of these ten tablets was 10.165 g. A 1.830 g sample of the finely ground tablets was dissolved in an acidic solution. The solution was neutralized with ammonia and subsequently warmed in a water bath. Addition of (NH4)3PO4 to the solution resulted in the precipitation of ZnNH4PO4. The precipitate was filtered and dried, then ignited to produce 0.234 g of Zn2P2O7 (molar mass = 304.76 g/mol). What is the mass percent of ZnSO4·7H2O in each tablet?
What is the average mass of the active ingredient ZnSO4·7H2O and inactive filler in each tablet?
In: Chemistry
HOI + NO = I2 + NO3-1 balance the following reaction in acid
In: Chemistry
Naphthalene is mostly insoluble in water. How would you recrystalize benzoic acid contaminated with naphthalene?
In: Chemistry