Surface tension of water and mercury: Effect of temperature
At 20 degrees celsius the surface tensions for water and mercury are 73dyn/cm and 470dyn/cm respectively. Find these values in SI units. A small capillary tube of 1mm diameter is placed into a container of 20 degree celsius water. will the level of the water in the tube move above or below the level of water? by what distance in meters? Next, calculate the volume and then the mass in kg. of the water being moved up or down. Repeat this problem for mercury.
What effect does temperature have upon surface tension? Is it better to wash clothes in hot water or cold water?
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Solution Preview
Surface tension of water = Tw = 73 dyn/cm
=> Tw = 73*10^(-5)/10^(-2) = 73*10^(-3) N/m = 0.073 N/m --Answer
Surface tension of Mercury = T(Hg) = 740 dyn/cm
=> T(Hg) = 740*10^(-3) N/m = 0.74 N/m --Answer
Diameter of capillary tube = 1 mm
=> r (radius of tube) = 0.5*10^(-3) m
because, contact (Q==theta) angle between glass and water is 0 degree, it implies that the water will rise up -- because the surface will be concave and in concave surface the pressure below the surface be less than the pressure above the surface. To balance this pressure, difference ...
Solution Summary
The detailed solution shows all the calculations together with explanations. The surface tension of water and mercury is given. The effects of temperature are provided.