Chemistry Answers

Given the following thermochemical equations:

1.) 4NH3)+302(g) → 2N₂(g) + 6H₂0 (1) ∆H°-1531 kJ

2.) N₂O(g) + H₂(g) → N₂(g) + H₂O(0) ∆H°-367.4 k]

3.) H₂(0)+02 (0)→ H₂0 (1)

∆H°= -285.9 kJ

Find the value of AH" for the reaction:

2NH3(g) + 3N₂0(g) → 4N₂(g) + 3H₂O(1)

Chlorine trifluoride is a colorless, poisonous, and corrosive gas. It is produced from the reaction between chlorine fluoride and fluorine gas.

CIF(g) + F2 (g) → CLF3 (9)

Determine the ∆H° for the overall reaction based on the three-step thermochemical process below:

1.) 2CLF(g) + O2(g) → Cl₂0(g) + F₂0 (g) ∆°H-167.5 k]

2.) 2C1F3(g) +202(g) → Cl₂0(g) + 3F₂0(g)

∆H° =-341.4 k]

3.) 3F₂0)→2F2 (g) + O2(g)

∆H° = 43.4 kJ

A system absorbs 50J of heat during a transformation. Determine the change in internal energy if 

the system perform, (a) 15J and (b) 65J of work on the surrounding.

Find the ∆E

a) When 175J of work is done on a system that evolves 50J of heat to the surrounding.

b) When a gas absorbs 28kJ of heat and 13kJ of work done on it.

2.83 g of a sample of haematite iron ore [iron (III) oxide, Fe₂O₃] were dissolved in concentrated hydrochloric acid and the solution diluted to 250 cm³. 25.0 cm³ of this solution was reduced with tin(II) chloride (which is oxidised to Sn⁴⁺ in the process) to form a solution of iron(II) ions. This solution of iron(II) ions required 26.4 cm³ of a 0.0200 mol/dm³ potassium dichromate(VI) solution for complete oxidation back to iron(III) ions.

(a) given the half–cell reactions 

(i) Sn⁴⁺_(aq) + 2e^– ==> Sn²⁺_(aq)

and (ii) Cr₂O₇^2–_(aq) + 14H⁺_(aq) + 6e^– ==> 2Cr³⁺_(aq) + 7H₂O_(l)

deduce the fully balanced redox equations for the reactions

(i) the reduction of iron(III) ions by tin(II) ions

(ii) the oxidation of iron(II) ions by the dichromate(VI) ion

(b) Calculate the percentage of iron(III) oxide in the ore. 

7. Use the oxidation number method to balance the following equations:

 a) Al_(s) + H₂SO_{4 (aq)} Al₂(SO₄)_{3 (aq)} + H_{2 (g)}

b) PbS_(s) + O_2(g) PbO _(s) + SO_{2 (g)}

How many gram of potassium and iodine present in one kilogram of KI

Use the half-reaction method to balance the following equation and then identify the oxidizing and reducing agents:

Fe(OH)_{2 (s)} + Pb(OH)₃ ^-_(aq)    →  Fe(OH)_{3 (s)} + Pb_(s) [basic]

The equilibrium constant kp for the oxidation of sulfur dioxide into sulfur trioxide is 5.6x10^4 at 350 celsius. if the equilibrium partial pressures of SO2 and SO3 are 0.64 atm and 0.58 atm, respectively,, what is the partial pressure of O2 in the system?

How many moles of helium would give a pressure of 900 mm Hg in 25.0 L vessel at

500C?

acetylene is formed by the reaction of water with calcium carbide according to the following eqation CaC2 +2H2O->Ca(OH)2 +C2H2 .how many grams of CaC2 would be needed to produce 10 L (measured at STP) acetylene .