Why would prefer to use the mercury instead the water in a sphygmomanometer?

1 Answer
Dec 30, 2016

Answer:

Because #1*atm# supports a column of mercury #760# #mm# high..........

Explanation:

But given the density of mercury compared to water (#rho_"Hg"=13.55*g*cm^-3; rho_"water"=1*g*cm^-3#, it would require a column of water approx. #10*m# high to support a pressure of #1*atm#.

Now sphygmomanometers take blood pressure measurements; typically we measure #50-60*mm# above or below atmospheric pressure. A measurement of a water column would still be prohibitively high.