Draw Cooling Curve for Hot Water
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What happens to the temperature of a block of ice when you put a Bunsen burner underneath it? You lot might think that the temperature goes up smoothly, but that's non what happens. The graph of temperature against time is called a heating bend. Let's look at the heating bend for water.
From- http://www.dlt.ncssm.edu/TIGER/Flash/phase/HeatingCurve.html
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Find that, in general, the temperature goes up the longer the heating continues. However, there are two horizontal flat parts to the graph. These happen when at that place is a change of country. The plateaus are also called stage changes .
The showtime alter of state is melting (changing from a solid to a liquid). The temperature stays the same while a substance melts. For water, this temperature is 0�C because the melting point for water is 0�C.
The second change of country is boiling (changing from a liquid to a gas). The temperature stays the aforementioned while a substance boils. For water, this temperature is 100�C because the boiling bespeak for water is 100�C .
Different substances have different melting points and boiling points, but the shapes of their heating curves are very similar. For case, this is the heating bend for fe, a metal that melts at 1538�C and boils at 2861�C.
Cooling Curves
Heating curves testify how the temperature changes as a substance is heated up. Cooling curves are the opposite. They show how the temperature changes as a substance is cooled down. Just like heating curves, cooling curves take horizontal flat parts where the state changes from gas to liquid, or from liquid to solid. You are likely to have used salol or stearic acid in a schoolhouse practical lesson to make your own cooling curve. Salol has a melting point of about 45�C and stearic acid has a melting point of virtually 69�C. They are easily melted in a boiling tube placed in a chalice of hot h2o. The temperature tin be followed using a thermometer or temperature probe connected to a data logger. The liquid may exist cooled past putting the humid tube in a beaker of cold water or but leaving it in the air.
***Note- The melting and freezing occur at the aforementioned temperature.
During freezing, energy is removed and during melting, energy is captivated.
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Kinetic Energy, Potential Energy and a Heating Curve.
Since Temperature is a mensurate of "Average Kinetic Free energy", any modify in temperature is a change in Kinetic Energy.
Since temperature does non change during a stage change, the energy that is gained or lost is Potential Free energy.
Remember the 3 Ps. Plateau, Phase change and Potential Energy Modify.
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eight/02
one The solid and liquid phases of water can exist in a state of equilibrium at 1 atmosphere of pressure and a temperature of
(1) 0oC (2) 100oC (3) 273oC (four) 373oC
| Reply---> | The melting signal of water is OoC or 273K |
two Given the equation: H2O(s) <--> HtwoO(l) At which temperature will equilibrium exits when the atmospheric pressure is one atm?
(1) 0 Thou (2) 100 1000 (three) 273 G (four) 373 K
| Respond---> | The melting point of water is OoC or 273K |
iii The table below shows the normal humid point of four compounds.
Which chemical compound has the strongest intermolecular forces? (1) HF(fifty) (2) CH3Cl(l) (3) CH3F(fifty) (4) HCl(l)
| ANSWER---> | HF The higher the boiling Point the stronger the force of attraction between the molecules |
A sample of water is heated from a liquid at 40oC to a gas at 110oC.
a) On the heating curve diagram provided above, label each of the following regions:
Liquid, only ; Gas, simply; Phase change
b) For section QR of the graph, state what is happening to the water molecules as heat is added.
c) For section RS of the graph, country what is happening to the h2o molecules as heat is added.
| Answer a---> | QR-liquid simply RS-Phase Change ST Gas only |
| Reply b---> | QR-Kinetic Free energy increases |
| Respond c---> | RS- Potential Free energy Increases |
3 The graph below represents the heating curve of a substance that starts every bit a solid below its freezing bespeak.
What is the melting point of this substance? (1) thirtyoC (2) 55oC (3) 90oC (4) 120oC
| Answer---> | 55 degrees the lower plateu is the melting/freezing point |
eight/03
Base your answers to questions 59 through 62 on the information below.
Given the heating bend where substance Ten starts every bit a solid beneath its melting indicate and is heated uniformly:
59 Identify the process that takes place during line segment DE of the heating curve.
| Reply---> | Vaporization, humid or phase change. NOT evaporation (that occurs below the boiling signal). |
sixty Identify a line segment in which the boilerplate kinetic energy is increasing.
| ANSWER---> | AVG. KE is temp, AB CD or EF |
61 Using "o" to stand for particles of substance X, draw at least five particles equally they would appear in the substance at indicate F.
| Reply---> | The five particles would be spread out. |
62 Describe, in terms of particle beliefs or free energy, what is happening to substance X during line segment BC.
| ANSWER---> | The particles are increasing in potential energy. |
Base your answers to questions 54 and 55 on the heating curve beneath, which represents a substance starting equally a solid below its melting indicate and being heated at a constant rate over a period of time.
54 What is happening to the average kinetic free energy of the particles during segment BC?
| ANSWER---> | Since Avg. KE is Temperature, it remains the aforementioned. |
55 How does this heating bend illustrate that the heat of vaporization is greater than the oestrus of fusion?
| ANSWER---> | Segment DE is Longer than BC. More energy requires more time. NOT DE is at a higher temp. |
six/05
17 In which process does a solid change directly into a vapor? (1) condensation (2) sublimation (3) degradation (4) solidification | ANSWER---> | Choice ii Sublimation |
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Affair Terminology Classifying Affair Phases of Matter Physical and Chemical Changes Separation Techniques Vapor Force per unit area Phase Changes Heating Curve Phase Diagrams
Source: http://www.kentchemistry.com/links/Matter/HeatingCurve.htm
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