P-1 Heat — Science STD 10 — Question

(i) The anomalous behavior of water can be studied with Hope's apparatus.
(ii) In Hope's apparatus, there is a metallic cylindrical container. At the middle of the cylinder, there is a flat bowl.
(iii) Two thermometer one at the upper region and other at the lower region is fixed to record the temperature.
(iv) The freezing mixture of salt and ice is taken in the flat bowl. Temperatures are recorded after every 30 min.
(v) Water of 10°C is poured into the cylindrical container. Initially, both the thermometers show the temperature of 10°C.
(vi) As the temperature of water decreases due to freezing mixture, it contracts, density increases and goes to the bottom of the container till 4°C.
(vii) Due to this, for sometime the thermometer at the bottom shows temperature of 4°C.
(viii) As the temperature falls below 4°C water in the region expands instead of contracting, density decreases and this water rises towards the surface.
(ix) After sometime, the upper thermometer shows the temperature of 0°C and the lower
thermometer shows 4°C.
(x) Finally both thermometer show 0°C
(xi) In this way, the anomalous behaviour of water can be demonstrated in the laboratory by using Hope's apparatus.