Amount of heat required at for unit rise in temperature at different temperatures of water - Physics Stack Exchange most recent 30 from physics.stackexchange.com 2019-06-27T02:07:09Z https://physics.stackexchange.com/feeds/question/95527 http://www.creativecommons.org/licenses/by-sa/3.0/rdf https://physics.stackexchange.com/q/95527 0 Amount of heat required at for unit rise in temperature at different temperatures of water PitifulStudent https://physics.stackexchange.com/users/38226 2014-01-27T17:28:59Z 2014-01-27T17:56:12Z <p>In my text book, it is given : </p> <blockquote> <p>One calorie is defined as the amount of heat required to raise the temperature of water from 14.5 °C to 15.5 °C.</p> </blockquote> <p>I found out in wikipedia that this is actually the definition of 15 °C calorie. </p> <p>I want to know that as temperature increases, will the amount of energy for unit increase in temperature decrease? I find 15 °C calorie > 20 °C calorie. Is this relation uniform till 100 °C or is there any anomaly? And does the increased kinetic energy of the molecules of water, at an elevated temperature cause the amount of heat - required for unit rise in temperature, to be greater than the amount of heat required for the same unit rise, but at a lower temperature?</p> <p>For example, the heat energy required to produce unit rise in temperature of water at 14.5 °C is 4.1855 joules and the amount of heat energy required to produce unit rise in temperature of water at 19.5 °C is 4.182 joules.</p> <p>So does the increased K.E of water molecules at 19.5 °C cause the required heat energy to be lower than the heat energy required at 14.4 °C?</p> https://physics.stackexchange.com/questions/95527/-/95529#95529 1 Answer by John Rennie for Amount of heat required at for unit rise in temperature at different temperatures of water John Rennie https://physics.stackexchange.com/users/1325 2014-01-27T17:56:12Z 2014-01-27T17:56:12Z <p>From the data <a href="http://www.engineeringtoolbox.com/water-thermal-properties-d_162.html" rel="nofollow noreferrer">presented here</a>:</p> <p><img src="https://i.stack.imgur.com/rxj1z.gif" alt="Cp of water"></p> <p>Note that although the scale of the \$y\$ axis makes the variation in \$C_p\$ look big it is only about 1% over the range 0 to 100°C.</p>