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2 NH 3 + H 2 SO 4 → (NH 4) 2 SO 4. A mixture of ammonia gas and water vapor is introduced into a reactor that contains a saturated solution of ammonium sulfate and about 2% to 4% of free sulfuric acid at 60 °C. Concentrated sulfuric acid is added to keep the solution acidic, and to retain its level of free acid.
With specific values for C a and K a this quadratic equation can be solved for x. Assuming [4] that pH = −log 10 [H +] the pH can be calculated as pH = −log 10 x. If the degree of dissociation is quite small, C a ≫ x and the expression simplifies to = and pH = 1 / 2 (pK a − log C a).
In aqueous solution, ammonia deprotonates a small fraction of the water to give ammonium and hydroxide according to the following equilibrium: . NH 3 + H 2 O ⇌ NH + 4 + OH −.. In a 1 M ammonia solution, about 0.42% of the ammonia is converted to ammonium, equivalent to pH = 11.63 because [NH +
For many substances, the formation reaction may be considered as the sum of a number of simpler reactions, either real or fictitious. The enthalpy of reaction can then be analyzed by applying Hess' law, which states that the sum of the enthalpy changes for a number of individual reaction steps equals the enthalpy change of the overall reaction.
The above equations (1, 2) run at a rate of 8.8×10 −9 and 4.4×10 −13, respectively. These calculations assumed the given rate constants and abundances of [NH 3]/[H 2] = 10 −5, [[H 3] +]/[H 2] = 2×10 −5, [HCO +]/[H 2] = 2×10 −9, and total densities of n = 10 5, typical of cold, dense, molecular clouds. [185]
, or the change in enthalpy of a reaction, has the same value of as in a thermochemical equation; however, is measured in units of kJ/mol, meaning that it is the enthalpy change per moles of any particular substance in an equation. Values of are determined experimentally under standard conditions of 1 atm [clarification needed] and 25 °C (298 ...
Fe 2 O 3 + 2 Al → Al 2 O 3 + 2 Fe This equation shows that 1 mole of iron(III) oxide and 2 moles of aluminum will produce 1 mole of aluminium oxide and 2 moles of iron . So, to completely react with 85.0 g of iron(III) oxide (0.532 mol), 28.7 g (1.06 mol) of aluminium are needed.
Relationship between cumulative association constant (β) values and stepwise dissociation constant (K) values for a tribasic acid. Equilibrium Relationship A 3− + H + ⇌ AH 2+ Log β 1 = pk a3: A 3− + 2H + ⇌ AH 2 + Log β 2 =pk a2 + pk a3: A 3− + 3H + ⇌ AH 3: Log β 3 = pk a1 + pk a2 + pk a3