CHEMICAL THERMODYNAMICS OF NICKEL

Chapter III

III Selected nickel data

This chapter presents the chemical thermodynamic data set for nickel species that has

been selected in this review. Table III–1 contains the recommended thermodynamic

data of the nickel compounds and species, Table III–2 the recommended thermodynamic

data of chemical equilibrium reactions by which the nickel compounds and complexes

are formed, and Table III–3 the temperature coefficients of the heat capacity data

of Table III–1 where available.

The species and reactions in the tables appear in standard order of arrangement.

Table III–2 contains information only on those reactions for which primary data

selections are made in Chapter V of this review. These selected reaction data are used,

together with data for key nickel species and auxiliary data selected in this review, to

derive the corresponding formation data in Table III–1. The uncertainties associated

with values for key nickel species and the auxiliary data are in some cases substantial,

leading to comparatively large uncertainties in the formation quantities derived in this

manner.

The values of r m Δ Gο for many reactions are known more accurately than would

be calculated directly from the uncertainties of the f m Δ Gο values in Table III–1 and auxiliary

data. The inclusion of a table for reaction data (Table III–2) in this report allows

the use of equilibrium constants with total uncertainties that are based directly on the

experimental accuracies. This is the main reason for including both Table III–1 and

Table III–2.

The selected thermal functions of the heat capacities, listed in Table III–3, refer

to the relation

p,m Cο (T) = a + b × T + c × T 2 + d × T –1 + i × T -1/2

A detailed discussion of the selection procedure is presented in Chapter V. It

may be noted that this chapter contains data on more species or compounds than are

present in the tables of Chapter III. The main reasons for this situation are the lack of

information for a proper extrapolation of the primary data to standard conditions in

some systems and lack of solid primary data in others.

A warning: The addition of any aqueous species and their data to this internally

consistent data base can result in a modified data set, which is no longer rigorous and

can lead to erroneous results. The situation is similar when gases or solids are added.

III. Selected nickel data

44

Table III–1: Selected thermodynamic data for nickel compounds and complexes. All

ionic species listed in this table are aqueous species. Unless noted otherwise, all data

refer to the reference temperature of 298.15 K and to the standard state, i.e., a pressure

of 0.1 MPa and, for aqueous species, infinite dilution (I = 0). The uncertainties listed

below each value represent total uncertainties and correspond in principle to the statistically

defined 95% confidence interval. Values obtained from internal calculation, cf.

footnotes (a) and (b), are rounded at the third digit after the decimal point and may

therefore not be exactly identical to those given in Part V. Systematically, all the values

are presented with three digits after the decimal point, regardless of the significance of

these digits. The data presented in this table are available on computer media from the

OECD Nuclear Energy Agency.

fGmΔ ο fHmΔ ο Smο Cp,m ο

Compound

(kJ · mol–1) (kJ · mol–1) (J · K–1 · mol–1) (J · K–1 · mol–1)

Ni(cr)

0.000

±0.000

0.000

±0.000

29.870

±0.200

26.070

±0.100

(c)

Ni(g)

384.686

±8.400

(a) 430.100

±8.400

182.190

±0.080

23.360

±0.100

Ni(l)

14.035

±0.272

(a) 17.500

±0.250

41.490

±0.300

Ni2+

– 45.773

±0.771

(b) – 55.012

±0.878

(a) – 131.800

±1.400

(d) – 46.100

±7.500

NiO(cr)

– 211.660

±0.422

(a)