Question

Observation of hopes apparatus with his application and working

Answer 1

Thomas Charles Hope (1766-1844) was the Professor of Chemistry at Edinburgh University from 1795-1843. In 1805 he published a paper "Experiments and Observations upon the Contraction of Water by Heat at Low Temperatures". In it he showed that water has its maximum density at about 4°C, a fact well known to fish who congregate at the bottom of ponds in freezing weather.
The apparatus at the left is at Kenyon College, and at the right is an example of Hope's apparatus at the University of Cincinnati.






Hope's apparatus is a glass cylinder encircled with a trough half-way up to contain a freezing mixture. Holes in the cylinder at the top and the bottom allow thermometers to be inserted into the water to sample its temperature. After a sufficient length of time the more dense water collects at the bottom at a temperature of 4°C.
The reference below gives graphs of Hope's experiments (in his paper he only gave tables), plus additional experiments run by the author in 1981.
REFERENCE: Thomas B. Greenslade, Jr., "The Maximum Density of Water", Phys. Teach., 23, 474-477 (1985)

Answer 2

Aim:- take help of your teacher to make a working model of hope's apparatus and perform the experiment verify the result you obtain.

Conclusion:-It is a common experience that when a liquid is heated, it expands, irrespective of the temperature range. However, water is an exception. When water at 0 ºC is heated, it contracts till 4 ºC, instead of expanding. On further heating from 4 ºC, water expands like other liquids do. The special behaviour of water between 0ºC and 4ºC is called the anomalous behaviour of water.

Opinion:-This apparatus is used to determine the temperature at which water has the maximum density. Thick sheet metal construction with baked hammertone finish.

Method:-Hope's apparatus consists of a vertical vessel full of water surrounded round the middle by a trough of cooling ice. Two thermometers, one above and one below the trough, measure the temperature of the water. It is designed to demonstrate that water reaches its maximum density at 4 °C (39 °F).

Importance: - The anomalous expansion of water refers to the fact that water, unlike most substances, expands when it freezes. The density of water increases as temperature decreases, but reaches a maximum at 4 degrees C then begins to expand. The significance of this is that ice is less dense than water so it floats in water. Anomalous expansion of water is an abnormal property of water whereby it expands instead of contracting when the temperature goes from 4°C to 0°C, and it becomes less dense. Normally, liquids contract on cooling & the density increases. However, water is special. ... The density of ice is lower, and so it floats on water.