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The temperature of a substance depends on the amount of heat energy in it. So when you heat up water its temperature rises. However, when a substance changes state - when water boils, for instance - liquid water uses heat to become a gas. The amount of heat it takes to convert one gram of water (at 100 deg C) to gaseous water (at 100 deg c) is 539 cal.
That is, taking a gram of water from 99 deg C to 100 deg C consumes 1 calorie, but taking that liquid water to gaseous water takes another 539 calories. The heat overcomes the intermolecular attractive force - the cohesion of the liquid water molecules. But when you add the 540th calorie the gaseous water's temperature goes up to 101 deg C.
That is called the heat of vaporization. Similarly, the heat of fusion is the amount of heat energy it takes to liquefy ice - and the temperature stays at 0 deg C when you add nearly 80 calories to turn ice into liquid water.
In other words, melting ice takes as much energy as it would take to raise the temperature of liquid water from 0 deg C to 79.7 deg C.
What else can I help you with?
Explain why the temperature of Wax remains constant during solidification?
it's because it releases the latent heat of fusion. Latent heat means energy is given out when a substance changes from liquid to solid without a change in temperature. and the transfer of energy doesnt change the KE of the particles, so the temperature remains unchanged. lanten heat gives rise to the change in PE of the particles during the change of state only
A change in matter which doesnt change the individual molecules?
A change in matter that does not change the individual molecules is a physical change. During a physical change, the substance retains its molecular structure but undergoes a change in properties such as shape, size, or state (solid, liquid, gas). Examples include melting, freezing, dissolving, and phase changes.
Is the fermenting of cheese a physical change?
"A physical change is any change not involving a change in the substance's chemical identity. Matter undergoes chemical change when the composition of the substances changes: one or more substances combine or break up (as in a relationship) to form new substances" From This I gather that its a physical change as the cheese isn't changed into another substance, The cheese doesnt change, for example it doesnt taste or smell different, But its physical propertys do change it looks different
Is a boiling point a chemical or physical property?
The boiling point is a physical property of a substance. It is the temperature at which the vapor pressure of the liquid is equal to the atmospheric pressure, causing the liquid to change into a gas phase.
16 Why is the state of matter a physical property and not a chemical property?
A physical property can be found without changing the composition of the substance. when you are finding the density of an object, you simply have to divide the object's mass by its volume. There is no chemical change occurring.
What doesnt change during the composition of a substance?
The composition of a chemical compound is not changed during a physical change.
Is it true that a star doesnt change its size or temperature during its life?
No, that's not true.
What is a property of matter that doesnt change a substance into a new substance?
Physical property of matter
Why does the temperature not change during a phase change?
During the change of state, the molecules of a substance absorb energy to overcome the strong intermolecular force of attraction between them. Hence the heat energy which we supply is absorbed by them for this purpose. So change in temperature is not observed.
Explain why the temperature of Wax remains constant during solidification?
it's because it releases the latent heat of fusion. Latent heat means energy is given out when a substance changes from liquid to solid without a change in temperature. and the transfer of energy doesnt change the KE of the particles, so the temperature remains unchanged. lanten heat gives rise to the change in PE of the particles during the change of state only
When a physical change in a sample occurs which does not change?
Substance in the material Remain the same
When liquid is boiling its temp doesnt change?
At the boiling point the temperature remain unchanged.
a change in the chemical properties of substance results in a?
A substance can take on three physical states: Solid, liquid, or gas. The main physical changes from a thermodynamic standpoint are the amount of entropy(disorder) of the molecules of the substance. Density, temperature, volume are also characteristically different at each physical state and can be used to manipulate compounds between the three.
Why doesnt air temperature change uniformly with altitude?
Altitude doesn't change uniformly because the four main layers of the atmosphere have different temperature gradients, creating the thermal structure of the atmosphere.
Did the temperature fluctuate while the is melting?
No. The temperature does not change during the melting process. All of the heat energy is used to break the bonds of the solid to form a liquid, i.e. the energy is used in the phase change, and thus is not used to raise the temperature.
What is Heating up metal with a flame is that a physical or chemical change?
No, it is a chemical change. The metal oxide formed is a new substance.
Why doesnt temperature change when transferring from ice too water?
The thermal energy required to change state is taken from the environment; which in this case is the melt water.
