meniscus definition. A concave surface of a liquid resulting from surface tension. The bottom of the meniscus is used to measure the volume of a liquid in apparatus such as a graduated cylinder.

A meniscus occurs because of surface tension in the liquid and must be read at eye level. For a concave meniscus, the correct volume will be read at the bottom of the curve. For a convex meniscus, the opposite is true and the correct reading will be at the top of the curve.

Explanation: When it curves upwards it reveals that the liquid has stronger adhesive force than cohesive force. When meniscus of liquid curves upward in a calibrated container the volume of the liquid is determined by reading the values at the bottom of the curving point.

Normally, liquid will curve at the edges of the surface where the liquid touches the container because water molecules are more attracted to glass than to each other. We need to read the level at the bottom of the meniscus to measure a volume of liquid in a graduated cylinder.

A solid has definite volume and shape, a liquid has a definite volume but no definite shape, and a gas has neither a definite volume nor shape. The change from solid to liquid usually does not significantly change the volume of a substance.

Fixed volume is the property of liquid and solid. Which shows that the volume of both solid and liquid remain fixed under fixed temperature and pressure. Unlike gases, where the volume changes without applying any external force.

The closeness, arrangement and motion of the particles in a substance change when it changes state. the movement of its particles increases. bonds between particles break when a substance melts or evaporates, or sublimes to form a gas from a solid.

When 1 mol of water vapor at 100°C condenses to liquid water at 100°C, 40.7 kJ of heat are released into the surroundings.

Adding Energy: When a solid is at its melting point, any energy added to it is used to overcome the attractions that hold the particles in place.

The condensation is the opposite process of evaporation. The heat of condensation is numerically exactly equal to the heat vaporization, but has the opposite sign. In the case of evaporation, the energy is absorbed by the substance, whereas in condensation heat is released by the substance.

As water vapor condenses into liquid, it loses energy in the form of heat. Therefore, this process is exothermic.

Note that melting and vaporization are endothermic processes in that they absorb or require energy, while freezing and condensation are exothermic process as they release energy.

Water is able to absorb heat – without increasing much in temperature – better than many substances. This is because for water to increase in temperature, water molecules must be made to move faster within the water; this requires breaking hydrogen bonds, and the breaking of hydrogen bonds absorbs heat.

Water reflects most solar radiation that reaches its surface back to the atmosphere. Since land absorbs more solar radiation the land surface retains more heat as do the vegetation for energy. Thus, land surfaces warm more quickly than water.

One of water’s most significant properties is that it takes a lot of heat to it to make it get hot. Precisely, water has to absorb 4,184 Joules of heat (1 calorie) for the temperature of one kilogram of water to increase 1°C. For comparison sake, it only takes 385 Joules of heat to raise 1 kilogram of copper 1°C.

These include copper (92), iron (11), water (0.12), and wood (0.03). At the opposite end of the spectrum is a perfect vacuum, which is incapable of conducting heat, and is therefore ranked at zero. Materials that are poor conductors of heat are called insulators.

Researchers have discovered that tantalum carbide and hafnium carbide materials can withstand scorching temperatures of nearly 4000 degrees Celsius.

Materials that absorb sunlight well include dark surfaces, water and metal. The sun’s light energy arrives as a mixture of visible light, ultraviolet and infrared; some materials absorb all these wavelengths well, while others are better suited to a certain restricted types of light.

Many solar installations harvest energy by converting sunlight to heat; metal components efficiently absorb and transfer heat while withstanding high temperatures. For solar applications that use mirrors, thin coatings of silver, aluminum and other metals serve as good reflectors of light.

In your home, materials with shiny, reflective surfaces can deflect heat to keep your home cooler. Foams and insulations are also common materials used to reduce heat transfer in your home to make it more efficient.