Science, asked by nikhil5292, 1 year ago

temperature in hopes apparatus after one minute gap

Answers

Answered by jacobcunningham202
1

im:- 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

Answered by NahakAnkit
1
The goal of this experiment is to demonstrate that between the temperatures 0 °C and 4 °C, the density of water increases with increasing temperature. (To be exact: we are going to demonstrate that water has a higher density at 4 °C than at 0 °C.)

Theory: thermal volume expansion of liquids

The volume of liquids is, similarly to solids and gases, dependant on their current temperature. Liquids (with the exception described below) increase their volume with increasing temperature; the increase of their volume ΔV is, with some neglect, directly proportionate to increase of temperature Δt and the initial volume V0. This relation can be mathematically denoted as

ΔV≐βV0Δt,(1)(1)ΔV≐βV0Δt,

where the constant β describes the volumetric thermal expansion coefficient and is a characteristic property of every liquid. (The neglect mentioned above limits the validity of this relationship to “small” differences in temperature, where βΔt≪1.). The volume of the liquid V after heating is therefore equal to the sum of its initial volume Vo and the growth ΔV given by relationship (1):

V≐V0+βV0Δt=V0(1+βΔt).(2)(2)V≐V0+βV0Δt=V0(1+βΔt).

Relationship (2) can be expanded using mass and density:

mρ≐mρ0(1+βΔt),(3)(3)mρ≐mρ0(1+βΔt),

which can be simplified to:

ρ≐ρ01+βΔt.(4)(4)ρ≐ρ01+βΔt.

The result is logical and predictable – if the volume of a liquid increases with increasing temperature, its density (while conserving mass) necessarily decreases.

Theory: anomaly of water

The constant β used in the relationships above is itself dependent on temperature; this dependence is usually very small. In the case of water, however, β has negative values in the narrow range between 0 °C and 4 °C. Heating water inside this interval therefore leads to a decrease in volume, or an increase in density. This phenomenon, unobserved in other liquids, is often referred to as the anomaly of water.

The volume of water is then apparently minimal (and the density maximal) at approx. 4 °C; exceeding this temperature leads to the values of β becoming positive again and a subsequent increase in temperature causes an increase in volume (decrease in density), in agreement with the general theory.

The dependence of (distilled) water on temperature is illustrated by Fig. 1.



Tools

Hope's device, two thermometers (two sensors connected to a computer, which can plot the development of temperature in time; useful, though not necessary. In this experiment, two identical Vernier Go!Temp sensors were used.), crushed ice, kitchen salt, two large beakers (or other containers, preferably 500 ml or bigger).

Hope's device

A simple device demonstrating the anomaly of water was designed in 1805 by Scottish scientist Thomas Charles Hope (1766-1844), among others the discoverer of strontium. The picture below (Fig. 2) is taken from Wikipedia.

Similar questions