Question

slader A barometer accidentally contains 6.5 inches of water on top of the mercury column (so there is also water vapor instead of a vacuum at the top of the barometer). On a day when the temperature is 70oF, the mercury column height is 28.35 inches (corrected for thermal expansion). (a) Determine the barometric pressure in psia. If the ambient temperature increased to 85oF and the barometric pressure did not change, (b) would the mercury column be longer, be shorter, or remain the same length

Answer 1

Step-by-step explanation:

vapour pressure at 70⁰F = .36 psi

pressure of 6.5 inch water column

6.5 inch = 6.5 x 2.54 cm =.165 m

pressure = .165 x 10³ x 9.8 = 1617 Pa

= 1617 x .000145 psi

= .23 psi

28.35 inch = 28.35 x 2.54 cm = .72 m

pressure = .72 x 13.6 x 10³ x 9.8

= 95961.6 Pa

= 95961.6 x .000145 psi

= 13.91 psi

a ) Barometric pressure at 70⁰F

= pressure due to mercury column of 28.35 inch + water column of 6.5 inch + vapour pressure at 70⁰F

= 13.91 + .23 + .36 psi

= 14.5 psi

b )

If pressure is measured at 85⁰F

vapour pressure will be increased and pressure of dry gas will also be increased . This pressure will force down the column of mercury . So column of mercury will go down .