critical pointn.

Brit.

/ˌkrɪtᵻkl ˈpɔɪnt/,

/ˈkrɪtᵻkl ˌpɔɪnt/, U.S.

/ˌkrɪdək(ə)l ˈpɔɪnt/,

/ˈkrɪdək(ə)l ˌpɔɪnt/

Origin: Formed within English, by compounding. Etymons: critical adj., point n.¹

Etymology: < critical adj. + point n.¹

1. Mathematics. A point at which the first-order derivatives of a function are either zero or indeterminate. Cf. stationary point n. 5.

ΚΠ

1848 B. Price Treat. Infinitesimal Calculus ix. 173 With this object we shall equate dy/dx to 0 and 1/0, and examine the course the curve takes at these critical points.

1959 N. B. Haaser et al. Course Math. Anal. I. x. 417 The function f has a critical point at 0. Since f'(0) does not exist we cannot apply Theorem 5.6.

2007 D. Szecsei Calculus xiii. 224 Calculus will help us determine whether a critical point is a local maximum or local minimum, or neither. The term local extrema refers to either local maxima or local minima.

2. Physical Chemistry. The temperature, and (in later use) the corresponding pressure, at which the liquid and vapour phases of a fluid become indistinguishable (cf. supercritical adj. 4); this point on a phase diagram (marked by the extreme end of the line representing the equilibrium of these phases); (also more widely) an analogous point for the liquid phases of a mixture.

ΘΚΠ

the world > matter > chemistry > physical chemistry > phases > [noun] > critical points > critical temperature

critical point1870

critical temperature1870

1870 T. Andrews in Philos. Trans. 1869 (Royal Soc.) 159 583 The point at which, by compression alone, carbonic acid is capable of assuming visibly the liquid form. Since I first announced this fact in 1863, I have made careful experiments to fix precisely the temperature of this critical point in the case of carbonic acid.

1876 P. G. Tait Lect. Recent Adv. in Physical Sci. xiii. 336 The temperature rises to the critical point, i.e. the temperature at and above which the presence of liquid and vapour together becomes impossible.

1933 J. K. Roberts Heat & Thermodynamics (ed. 2) iv. 100 The liquid and vapour densities..are determined as near to the critical point as is practicable, and..the results are extrapolated to the point itself.

1976 Proc. Royal Soc. London A. 350 101 The difference between the compositions of the two phases tends to zero as the critical point is approached along the coexistence curve.

2012 E. A. Baskharone Thermal Sci. ii. 16 The vaporization line ends at the critical point, above which no distinction can be made between the liquid and vapor phases.

This entry has been updated (OED Third Edition, March 2022).

单词	critical point
释义	critical pointn. Brit. /ˌkrɪtᵻkl ˈpɔɪnt/, /ˈkrɪtᵻkl ˌpɔɪnt/, U.S. /ˌkrɪdək(ə)l ˈpɔɪnt/, /ˈkrɪdək(ə)l ˌpɔɪnt/ Origin: Formed within English, by compounding. Etymons: critical adj., point n.¹ Etymology: < critical adj. + point n.¹ 1. Mathematics. A point at which the first-order derivatives of a function are either zero or indeterminate. Cf. stationary point n. 5. ΚΠ 1848 B. Price Treat. Infinitesimal Calculus ix. 173 With this object we shall equate dy/dx to 0 and 1/0, and examine the course the curve takes at these critical points. 1959 N. B. Haaser et al. Course Math. Anal. I. x. 417 The function f has a critical point at 0. Since f'(0) does not exist we cannot apply Theorem 5.6. 2007 D. Szecsei Calculus xiii. 224 Calculus will help us determine whether a critical point is a local maximum or local minimum, or neither. The term local extrema refers to either local maxima or local minima. 2. Physical Chemistry. The temperature, and (in later use) the corresponding pressure, at which the liquid and vapour phases of a fluid become indistinguishable (cf. supercritical adj. 4); this point on a phase diagram (marked by the extreme end of the line representing the equilibrium of these phases); (also more widely) an analogous point for the liquid phases of a mixture. ΘΚΠ the world > matter > chemistry > physical chemistry > phases > [noun] > critical points > critical temperature critical point1870 critical temperature1870 1870 T. Andrews in Philos. Trans. 1869 (Royal Soc.) 159 583 The point at which, by compression alone, carbonic acid is capable of assuming visibly the liquid form. Since I first announced this fact in 1863, I have made careful experiments to fix precisely the temperature of this critical point in the case of carbonic acid. 1876 P. G. Tait Lect. Recent Adv. in Physical Sci. xiii. 336 The temperature rises to the critical point, i.e. the temperature at and above which the presence of liquid and vapour together becomes impossible. 1933 J. K. Roberts Heat & Thermodynamics (ed. 2) iv. 100 The liquid and vapour densities..are determined as near to the critical point as is practicable, and..the results are extrapolated to the point itself. 1976 Proc. Royal Soc. London A. 350 101 The difference between the compositions of the two phases tends to zero as the critical point is approached along the coexistence curve. 2012 E. A. Baskharone Thermal Sci. ii. 16 The vaporization line ends at the critical point, above which no distinction can be made between the liquid and vapor phases. This entry has been updated (OED Third Edition, March 2022). < n.1848
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