What is Temperature?
The hotness and coldness of an object is its temperature. The units of temperature are ℃, ℉, and K. The units of temperature were named after the name of the following scientists:
℃ = Anders Celsius
℉ = Daniel Gabriel Fahrenheit
Thermodynamic Temperature - K = William Thomson, 1st Baron Kelvin
High temperature affects the oceans, weather, snow/ice, plants, and animals. The warmer the environment becomes, the harder the survival of living beings becomes. A rising temperature and its effects can be seen in a sudden change in weather, on PV cell characteristics, on the rate of reactions in Chemistry, and so on.
Impact of Temperature
In this article, we learn the rise of temperature and its effects on the following places:
On viscosity of fluids: liquids and gases
On internal resistance
The rate of reaction
On weather and climate
Impact of Temperature on Viscosity
We know that fluids comprise two things viz: liquid and gas. The molecules in the liquid are close to each other, while in gases, these molecules are far away.
Impact of Temperature on Viscosity of Liquids
When you heat a liquid, the intermolecular distance increases. As we know, liquids have a good amount of cohesive force between the molecules that resist its easy flow over the surface. On raising the temperature, the strength of cohesive forces decreases, which, in turn, decreases the resistance to flow in the liquid.
We also know that the resistance to the liquid flow is viscosity. When the temperature rises, the liquid viscosity decreases.
A practical example can be seen in vehicles.
During winters you find it difficult to start your two-wheeler with the self-start.
What you do is, apply three-to-four kicks with the choke pulled up. Do you know why we do this? Let’s understand it:
After applying kicks, your engine sets. As soon as your scooter starts, you keep it started in a standing position till the oil in the vehicle melts because in the winter season, the oil becomes thick or solidifies, i.e., attains higher viscosity, so when the temperature in the vehicle rises by the power offered through the kick, the oil becomes thin (viscosity of the oil decreases) and you’re all set to drive your two-wheeler now.
You can find the graph for the above scenario below:
(Image to be added soon)
Now, talking about the impact of temperature on gases
Impact of Temperature on the Viscosity of Gases
In the case of gases, when the temperature rises, the gas molecules collide with each other because of which the resistance increases. It means that the viscosity of gases increases with the temperature rise. So the graph for this case will be:
(Image to be added soon)
Impact of Temperature on Internal Resistance
On increasing the temperature of the conductor, the kinetic energy of electrons increases, which means the relaxation time decreases. When the relaxation time decreases, then by the following relationship:
R = \[\frac{ml}{ne^{2}A\tau }\]
Where,
N = electron density
τ = relaxation time
l = length of the wire
m = mass of an electron
A = cross-sectional area
e = charge
The change in the resistance of conductors depends upon the following factors:
Internal resistance
Change in temperature Δt
From the above equation, we can see that R ∝ 1/τ . So, when the temperature increases, the resistance of the conductor also increases.
Impact of Temperature on the Rate of Reaction
Let us study the reaction of oxalic acid with potassium permanganate in the presence of sulphuric acid:
Take 0.5 g of oxalic acid (C2H2O4) crystals and dissolve them in 20 ml of water in a beaker to make a solution. Now, pour 5 ml of dilute H2SO4 into the solution and add a few drops of KMnO4 solution into the mixture.
What Do You Observe?
The solution turns pink. Now, stir the solution with a glass rod. After some time, the solution remains pink.
Now, prepare the solution of oxalic acid as we did earlier with the same quantities. Now, heat the solution to 60-80 ℃ and add a few drops of KMnO4 solution to it. You observe that while stirring the solution it becomes colourless.
Our desired result was to obtain a colourless solution. Now, as the solution becomes hot, the rate of reaction of the reaction of C2H2O4 with KMnO4 increases, and the colour disappears.
Impact of Temperature on Weather and Climate
The rise in temperature leads to global warming. It can cause the following environmental issues:
It can reduce the water levels in oceans,
Sudden changes in climatic conditions
Melting of ice in glaciers
Depletion of the ozone layer and the direct reach of UV-rays to the Earth’s surface.
The rise in temperature leads to the spread of heat waves; these heatwaves lead to illnesses like heat cramps, heat strokes, and even death.
We face many health issues like skin diseases, dryness, ecological imbalance, global warming, and so on.
FAQs on Impact of Temperature
1. What is the main difference between heat and temperature?
Temperature measures the average kinetic energy of particles in an object (how hot or cold it is), while heat is the total energy transferred from a hotter object to a colder one. Here are the key differences:
- Measurement: Temperature measures the degree of hotness. Heat is a form of energy.
- Unit: Temperature is measured in Celsius, Fahrenheit, or Kelvin. Heat is measured in Joules or calories.
- Instrument: A thermometer measures temperature, while a calorimeter measures heat.
2. How does a change in temperature affect common materials like solids and liquids?
When temperature increases, most materials expand. This is because heating gives their particles more energy, causing them to move faster and spread apart. For example, solids expand slightly, which is why bridges have expansion joints. Liquids expand more noticeably, which is the principle behind liquid-in-glass thermometers. Gases expand the most, as their particles are already far apart and move freely.
3. Can you give a real-world example of how temperature affects the viscosity of a liquid?
A great example is engine oil in a car. When the engine is cold, the oil is thick and has high viscosity, meaning it flows slowly. As the engine runs and heats up, the oil's temperature increases. This causes its viscosity to decrease, allowing it to flow more easily and lubricate the engine parts effectively. Another common example is honey, which becomes much easier to pour when warmed.
4. In what ways does temperature impact the environment?
Temperature is a critical factor that shapes our environment. It directly influences weather patterns by creating high and low-pressure systems, which lead to wind, rain, and storms. Over the long term, average temperature changes can alter climate, affecting everything from sea levels to the growth seasons for plants. It also determines the habitats where different plants and animals can survive.
5. Why do solids, liquids, and gases expand differently when heated?
The difference in expansion is due to the intermolecular forces and the arrangement of particles in each state.
- In solids, particles are tightly packed with strong forces, so they can only vibrate more in their fixed positions, leading to small expansion.
- In liquids, particles have weaker forces and can move past each other. Heating allows them to move faster and further apart, causing more expansion than in solids.
- In gases, particles have almost no forces between them and are very far apart. Extra energy from heat causes them to move much faster and spread out significantly, resulting in the largest expansion.
6. How does temperature affect the rate of chemical reactions?
Generally, increasing the temperature speeds up a chemical reaction. This happens for two main reasons. First, higher temperature means particles have more kinetic energy, so they move faster and collide more frequently. Second, and more importantly, more particles will have enough energy (called activation energy) to result in a successful reaction upon collision. This is why cooking food is faster at a higher heat.
7. What happens to the electrical resistance of conductors and semiconductors as temperature increases?
The effect of temperature on resistance is opposite for conductors and semiconductors. For most conductors, like copper wire, an increase in temperature causes resistance to increase. This is because the metal ions vibrate more, obstructing the flow of electrons. For semiconductors, like silicon, an increase in temperature causes resistance to decrease because more electrons gain enough energy to break free and carry a current.
8. Is it possible for an object to have a lot of heat energy but a low temperature?
Yes, this is a key concept that highlights the difference between heat and temperature. Heat depends on both the temperature and the mass of an object. For example, a massive iceberg at 0°C has a very low temperature, but because it has an enormous number of water molecules, its total heat energy is huge. In contrast, a tiny spark from a fire may have a very high temperature (over 1000°C), but it has very little mass and therefore contains very little heat energy.
