Table 5. Composition of the pre-eruption vapor present in the dacite of the climactic June 15, 1991, eruption, Mount Pinatubo

[Mt, megaton; Tmol, teramole (10^(12) mol); MPa, megapascal]

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Component       Mass(1)     Moles(1)      Mole     Pressure
                 (Mt)        (Tmol)      Percent     (MPa)
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PSO2 = 11 MPa:
     H2O         95.6        5.3073       80.1       220
     SO2         17.         0.2654        4.0        11
     CO2         42.5        0.9650       14.5        40
     Cl           3.2        0.0911        1.4         3.8
       Totals:  158.3        6.6288      100.0       274.8

PSO2 = 2 MPa:
     H2O        525.9       29.1901       82.9       220
     SO2         17.         0.2654        0.8         2
     CO2        233.6        5.3073       15.1        40
     Cl          16.1        0.4560        1.2         3.4
       Totals:  792.6       35.2188      100.0       265.4
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(1)Minimum estimates, as discussed in the text; extra 
significant figures for Moles to avoid round-off errors.