Vapor Pressure of Water (Handbook of Chemistry and Physics (1992-93))

 

Temp (oC)

VP (kPa)

 

Temp (oC)

VP (kPa)

 

Temp (oC)

VP (kPa)

0

0.61129

 
34

5.3229

 

67

27.347

1

0.65716

 

35

5.6267

 

68

28.576

2

0.70605

 
36

5.9453

 

69

29.852

3

0.75813

 
37

6.2795

 

70

31.176

4

0.81359

 
38

6.6398

 

71

32.549

5

0.8726

 
39

6.9969

 

72

33.972

6

0.93537

 
40

7.3814

 

73

35.448

7

1.0021

 
41

7.784

 

74

36.978

8

1.073

 
42

8.2054

 

75

38.563

9

1.1482

 
43

8.6463

 

76

40.205

10

1.2281

 
44

9.1075

 

77

41.905

11

1.3129

 
45

9.5895

 

78

43.665

12

1.4027

 
46

10.094

 

79

45.487

13

1.4979

 
47

10.62

 

80

47.373

14

1.5988

 
48

11.171

 

81

49.324

15

1.7056

 

49

11.745

 

82

51.342

16

1.8185

 

50

12.344

 

83

53.428

17

1.938

 

51

12.97

 

84

55.585

18

2.0644

 

52

13.623

 

85

57.815

19

2.1978

 

53

14.303

 

86

60.119

20

2.3388

 

54

15.012

 

87

62.499

21

2.4877

 

55

15.752

 

88

64.958

22

2.6447

 

56

16.522

 

89

67.496

23

2.8104

 

57

17.324

 

90

70.117

24

2.985

 

58

18.159

 

91

72.823

25

3.169

 

59

19.028

 

92

75.614

26

3.3629

 

60

19.932

 

93

78.494

27

3.567

 

61

20.873

 

94

81.465

28

3.7818

 

62

21.851

 

95

84.529

29

4.0078

 

63

22.868

 

96

87.688

30

4.2455

 

64

23.925

 

97

90.945

31

4.4953

 

65

25.022

 

98

94.301

32

4.7578

 

66

26.163

 

99

97.759

33

5.0335

 

 

 

 

 

 

101.325 kPa = 1 atm, 1 atm = 760 mm Hg

To determine the vapor pressure at non-whole number temperatures

Suppose you need to determine the vapor pressure of water at 25.4C. You know that at 24.0C the vapor pressure is 2.985 kPa and at 25.0C it is 3.169 kPa.

1.     Determine the difference between the two pressures: 3.169 - 2.985 = 0.184 kPa.

2.     Multiply the difference by the decimal portion (ONLY!) of the desired temperature: 0.184 x 0.4 = 0.0736 kPa.

3.     Add this value to the LOWER pressure you used in the first step: 2.985 + 0.0736 = 3.0586 kPa.

4.     Round off to the appropriate number of significant figures. In this case, the answer would be 3.059 kPa.