Thermal Energy and Specific Heat Capacity

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Questions and Answers

What is the unit of specific heat capacity?

kg J–1 K

J kg K–1

J kg–1 K–1 (correct)

J K kg–1

As the specific heat capacity of a substance increases, what can be said about the energy required to change its temperature?

More energy is required. (correct)

Less energy is required.

Energy requirement varies unpredictably.

Energy requirement remains constant.

Using the equation Q = mcΔT, what does 'ΔT' represent?

The temperature change. (correct)

The mass of the substance.

The specific heat capacity.

The total energy transferred.

If the specific heat capacity of a substance is very high, what is the impact on the time it takes for the substance to reach a certain temperature?

It takes longer to warm up or cool down. Signup and view all the answers

In the example provided, if the water cools from 20°C to 18°C, what can be inferred about the energy exchange between the copper and water?

Copper absorbs energy from the water. Signup and view all the answers

According to Boyle's Law, what happens to the product of pressure and volume for a fixed mass of gas?

It remains constant under all conditions. Signup and view all the answers

For Charles's Law, what must be true about the temperature scale used?

It must be measured in degrees Kelvin. Signup and view all the answers

What do Gay Lussac's and Boyle's laws have in common?

Both require a fixed mass of gas. Signup and view all the answers

If the volume of a gas at constant pressure doubles, what happens to the temperature (in kelvin) according to Charles's Law?

It doubles. Signup and view all the answers

What does Gay Lussac's Law specifically measure in relation to pressure and temperature?

Volume must remain constant. Signup and view all the answers

How can Boyle's Law be expressed mathematically?

p1V1 = p2V2 Signup and view all the answers

In the context of gas laws, what is the relationship between volume and pressure according to Boyle's Law?

Volume is inversely proportional to pressure. Signup and view all the answers

When plotting temperature against pressure for a fixed volume of gas, what shape does the graph typically take?

A straight line. Signup and view all the answers

What is the specific heat capacity of water?

4200 J kg–1 K–1 Signup and view all the answers

What is the mass of the copper used in the calculations?

2 kg Signup and view all the answers

What is the change in temperature of the water during the process?

-2°C Signup and view all the answers

How much thermal energy is transferred from the water to the copper?

-42000 J Signup and view all the answers

What is the equation used to determine thermal energy in this scenario?

Q = mcΔT Signup and view all the answers

What is the final temperature of the copper after gaining thermal energy?

44°C Signup and view all the answers

What is the specific heat capacity of copper?

390 J kg–1 K–1 Signup and view all the answers

Why is the energy lost by the water considered negative?

Because it reflects a decrease in temperature. Signup and view all the answers

What can improve the responsiveness of a thermometer?

Using a smaller bulb and thinner glass walls Signup and view all the answers

What is the formula for calculating the relative error in voltage?

δV = ΔV/V Signup and view all the answers

Which step involves summing all relative errors to determine the relative error on specific heat capacity?

Step 2 Signup and view all the answers

What unit is used for absolute errors in specific heat capacity measurements?

J kg–1 K–1 Signup and view all the answers

Which of the following is NOT a safety consideration when conducting experiments with a metal block?

Always use a larger metal block for safety Signup and view all the answers

What is the purpose of using insulating material around the metal block?

To minimize energy transfers with the surroundings Signup and view all the answers

How should the mass of the metal block be recorded?

With its uncertainty based on the scale's smallest division Signup and view all the answers

What is the initial step in measuring the temperature change of the metal block?

Measure and record the mass of the metal block Signup and view all the answers

How frequently should the temperature of the metal block be measured during the experiment?

Every minute (60 seconds) Signup and view all the answers

What is the purpose of sealing the air gap between the thermometer and the metal block?

To increase the temperature reading accuracy Signup and view all the answers

What value should be included in the results table along with the temperature measurement?

The uncertainty of the temperature measurement Signup and view all the answers

Which instrument has the least precise measurement in the provided apparatus?

Liquid-in-glass thermometer Signup and view all the answers

What should be done immediately after connecting the immersion heater to the power supply?

Start the stop-clock Signup and view all the answers

Study Notes

Specific Heat Capacity and Thermal Energy

Specific heat capacity is the amount of energy required to raise the temperature of 1 kg of a substance by 1 K (or 1°C).
The higher the specific heat capacity of a substance the more energy is needed to change its temperature.
The higher the specific heat capacity, the longer it takes for the substance to warm up or cool down.

Thermal Energy Equation

Thermal energy transferred, Q, is calculated using the formula: Q = mcΔT.
Where:
- m is the mass of the substance in kg.
- ΔT is the change in temperature in K or °C.
- c is the specific heat capacity of the substance in J kg⁻¹ K⁻¹.

Worked Example - Copper and Water

A 2 kg copper piece at -10°C placed in 5 kg of water at 20°C will result in the water cooling down to 18°C.
Energy is transferred from the water to the copper, as the water is at a higher temperature.
Using Q = mcΔT, the energy lost by the water is calculated to be -42,000 J (negative as energy is lost).
The energy gained by the copper is +42,000 J (positive as energy is gained).
The change in temperature (ΔT) of the copper can be calculated using the rearranged formula ΔT = Q/(mc).
The final temperature of the copper is calculated by adding its initial temperature to the change in temperature.

Boyle's Law

Boyle's Law states that for a fixed mass of gas at constant temperature, the volume of the gas is inversely proportional to its pressure.
This can be represented as pV = constant or p₁V₁ = p₂V₂.

Charles's Law

Charles's Law states that for a fixed mass of gas at constant pressure, the volume of the gas is directly proportional to its absolute temperature.
This can be represented as V/T = constant or V₁/T₁ = V₂/T₂.
The temperature must be measured in Kelvin (K) for this relationship to hold true.

Gay-Lussac's Law

Gay-Lussac's Law states that for a fixed mass of gas at constant volume, the pressure of the gas is directly proportional to its absolute temperature.
This can be represented as p/T = constant or p₁/T₁ = p₂/T₂.
The temperature must be measured in Kelvin (K) for this relationship to hold true.

Investigating Specific Heat Capacity

An experiment involving a metal block, immersion heater, thermometer, and power supply can be used to investigate the specific heat capacity of a metal.
The temperature change of the metal block over time is recorded.
The energy transferred to the metal block is measured.
The specific heat capacity is calculated using the formula c = Q/(mΔT).

Error Analysis

The relative error (δc) on the specific heat capacity can be determined by summing the relative errors of the measured quantities (voltage, current, temperature, mass, and time).
The absolute error (Δc) on the specific heat capacity can be calculated using the formula Δc = c x δc, where c is the experimental value of the specific heat capacity.

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Description

This quiz explores the concepts of specific heat capacity and thermal energy transfer. It covers the essential formula, examples using materials like copper and water, and the impact of specific heat on temperature changes. Test your understanding of how energy is transferred between substances.