Question

Water will rise up into a capillary tube. Why, and how is this phenomenon important in nature? Calculate the amount of heat in kJ that is required to heat 20.0 g of ice from -25 degree C to 90 degree C, and sketch a heating curve for the process. The specific heat of ice is 2.11 J/(g. degree C); water 4.18 J/(g. degree C) and the Delta H_fus for water is 6.01 kJ/mol Calculate the amount of heat liberated when a 10.0 g of steam is converted to water at 75.0 degree C and sketch a cooling curve for the process. The specific heat of steam is 2.00 J/(g. degree C); water are 4.18 J/(g. degree C) and the Delta H_vap for water is 40.6 kJ/mol.

Answer 1

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Water is good at capillary action. How well a liquid can perform the feat of capillary action depends on cohesion and adhesion. Cohesion is the attraction between particles of the same type. There is strong cohesion in water. One water molecule is strongly attracted to another. Adhesion is the attraction between two different particles. The adhesion between water molecules and a plastic straw is also strong.

Capillary action occurs when adhesive forces outweigh cohesive forces. Although water molecules are strongly attracted to each other, they are also attracted to the plastic of a straw. The result is that water molecules will climb up the surface of the interior of the straw and the level of the water is slightly higher within the straw. There is even better adhesion between water and glass as a result water level rise even higher in capillary tube.

Example: Plants use capillary action to bring water up the roots and stems to the rest of the plant. The molecules of the water are attracted to the molecules of the inside of the stem (the solid). This attraction is used to help force the water up from the ground and disperse throughout the plant.