Understanding Heat, Temperature, and Thermometers

Key Concepts of Heat and Temperature

1. What is the relationship between heat and kinetic energy?

   The relationship is directly proportional. Heat is a measure of the total kinetic energy of the individual particles in a substance. The higher the kinetic energy of the particles, the hotter an object feels.

2. How is temperature defined?

   Temperature is a measure that indicates how hot or cold an object is. It represents the average kinetic energy of the particles within that object.

3. Is heat the same as energy in transit?

   Yes, heat is a form of energy in transit. It is the energy that is transferred from one object to another due to a temperature difference between them.

4. When does thermal contact occur?

   Thermal contact occurs when heat can be transferred between two objects. This process stops once the objects reach the same temperature, a state known as thermal equilibrium, where the net transfer of heat ceases.

5. Why are certain substances useful for making thermometers?

   Certain substances are useful because they have properties, like volume, that change predictably and measurably with temperature. This consistent change allows for the creation of a reliable temperature scale.

6. Who invented the first thermometer?

   The first thermometer was invented by Galileo Galilei in 1602.

7. What is thermal expansion?

   Thermal expansion is the tendency of matter to change its shape, area, and volume in response to a change in temperature. It can refer to both expansion (an increase in size) and contraction (a decrease in size).

8. What is negative expansion?

   Negative expansion is the contraction of a substance, meaning it decreases in size as the temperature changes.

9. What fixed reference points are used to create a thermometer?

   The two primary fixed reference points are the freezing and boiling points of water under standard atmospheric pressure. These are the temperatures at which pure water freezes and boils, respectively.

10. Why are mercury and alcohol used in thermometers?

    These substances are chosen because they have a relatively large and uniform rate of thermal expansion over a wide range of temperatures, making them reliable for measurement.

11. What is the size difference between Celsius and Fahrenheit degrees?

    A change of 1 degree Celsius (°C) is equivalent to a change of 1.8 degrees Fahrenheit (°F). Therefore, a Fahrenheit degree is a smaller unit of temperature than a Celsius degree.

12. When are mercury and alcohol thermometers unreliable?

    These thermometers can give slightly different readings at temperatures between their fixed calibration points because their rates of expansion are not perfectly linear. They are also unreliable outside their specific liquid ranges (e.g., mercury freezes at -38.8°C, and alcohol boils at 78°C).

13. What type of thermometer is the most accurate?

    Gas thermometers are generally considered the most accurate type of thermometer and are often used as a standard for calibration.

Temperature Scale Conversions

14. What does the equation T_K = T_C + 273 mean?

    This equation shows how to convert a temperature from degrees Celsius (T_C) to Kelvin (T_K). It means the temperature in Kelvin is equal to the temperature in degrees Celsius plus 273.15 (often rounded to 273).

15. Convert 15°C to Kelvin.

    Using the formula:

    T_K = T_C + 273

    T_K = 15 + 273

    T_K = 288 K

16. Convert 152°F to Celsius.

    Using the formula:

    T_C = (T_F - 32) / 1.8

    T_C = (152 - 32) / 1.8

    T_C = 120 / 1.8

    T_C = 66.67°C