[SANGAT MUDAH] Cara menghitung kalor reaksi pada kalorimeter (PART 2)

Rumah Belajar MattPlus

29 Sept 202007:32

Summary

TLDRIn this educational video, the host discusses how to calculate the enthalpy of combustion using a calorimeter. The first problem involves the combustion of 8 grams of methane, resulting in a temperature rise from 25.5°C to 95°C in a 4-liter water calorimeter. Using the heat capacity of water and assuming the calorimeter's capacity is zero, the enthalpy of combustion is calculated to be -2184 kJ/mol. The second problem examines a reaction between nickel and CuSO4 solution, causing a 5°C temperature increase. The reaction's enthalpy is determined to be -4000 kJ/mol under standard conditions, showcasing the application of thermodynamics in chemical reactions.

Takeaways

🔍 The video discusses how to calculate the enthalpy change using a calorimeter.
🔥 The first problem involves the combustion of 8 grams of methane, resulting in a temperature rise in the calorimeter.
🌡️ The calorimeter's temperature increases from 25.5°C to 95°C due to the reaction.
💧 The calorimeter contains 4 liters of water, and the specific heat capacity of water is given as 4.2 J/g°C.
⚖️ The mass of the water in the calorimeter is calculated to be 4000 grams, assuming 1 liter is equivalent to 1 kilogram.
🔢 The change in temperature (ΔT) is calculated as the difference between the final and initial temperatures.
🔄 The enthalpy change of the reaction is calculated using the formula: \( \Delta H_{reaction} = -(mass_{water} \times c_{water} \times \Delta T) \).
🌐 The calorimeter's heat capacity is considered zero, simplifying the calculation.
🔄 The moles of methane burned are calculated by dividing the mass by the molar mass.
🔍 The final enthalpy change per mole of methane is determined by dividing the total enthalpy change by the moles of methane.
🧪 The second problem involves a reaction between nickel and a CuSO4 solution, causing a 5°C temperature increase in the solution.

Q & A

What is the mass of methane (CH4) burned in the first problem?
-The mass of methane (CH4) burned is 8 grams.
What is the initial and final temperature of the calorimeter in the first problem?
-The initial temperature is 25.5 degrees Celsius, and the final temperature is 95 degrees Celsius.
How much heat capacity does the calorimeter have in the first problem?
-The calorimeter is assumed to have a heat capacity of zero.
What is the heat capacity of water in the first problem?
-The heat capacity of water is 4.2 Joules per gram-degree Celsius.
How much heat is absorbed by the water in the first problem?
-The water absorbs 1092 kilojoules of heat.
What is the molar mass of methane (CH4) used in the first problem?
-The molar mass of methane (CH4) is 16 grams per mole.
What is the amount of methane (CH4) burned in moles in the first problem?
-Half a mole of methane (CH4) is burned.
What is the enthalpy change for the combustion of methane in kilojoules per mole in the first problem?
-The enthalpy change for the combustion of methane is -2184 kilojoules per mole.
What is the mass of nickel metal reacted with CuSO4 solution in the second problem?
-The mass of nickel metal reacted is 2.95 grams.
How much temperature increase is caused by the reaction of nickel metal with CuSO4 solution in the second problem?
-The reaction causes a 5-degree Celsius increase in the temperature of the solution.
What is the heat required to raise the temperature of the solution by 1 degree Celsius in the second problem?
-It requires 4 kilojoules of heat to raise the temperature of the solution by 1 degree Celsius.
What is the molar mass of nickel used in the second problem?
-The molar mass of nickel is 59 grams per mole.
How many moles of nickel are reacted in the second problem?
-0.05 moles of nickel are reacted.
What is the enthalpy change for the reaction of nickel with CuSO4 solution in kilojoules per mole in the second problem?
-The enthalpy change for the reaction is -40000 kilojoules per mole.

Outlines

00:00

🔍 Calculating Methane Combustion Enthalpy

The first paragraph discusses the calculation of the combustion enthalpy of methane using a calorimeter. It presents a problem where 8 grams of methane (CH4) are burned in a calorimeter, causing the temperature to rise from 25.5°C to 95°C. The calorimeter contains 4 liters of water with a specific heat capacity of 4.2 J/g°C. The calorimeter's heat capacity is considered zero. The calculation involves determining the temperature change (ΔT), the mass of water (converted to grams), and using the formula for reaction enthalpy (ΔH_reaction = -(C_water * m_water * ΔT)). The final step is to calculate the molar enthalpy of combustion by dividing the reaction enthalpy by the number of moles of methane burned (0.5 mol), resulting in -2184 kJ/mol.

05:01

🔬 Nickel Reaction with CuSO4 Solution Enthalpy

The second paragraph deals with the enthalpy change of a reaction between nickel metal and a CuSO4 solution, resulting in a temperature increase of the solution. Given data includes the mass of nickel (2.95g) and its molar mass (59 g/mol), and the heat required to raise the temperature of the solution by 1°C (4 J/g°C). Since the calorimeter's heat capacity is unknown, it is assumed to be zero. The calculation involves determining the heat change for the solution (ΔH_solution) and the reaction enthalpy (ΔH_reaction), which is the negative of the heat absorbed by the solution. The final calculation is to find the standard enthalpy of reaction per mole by dividing the reaction enthalpy by the number of moles of nickel reacted (0.05 mol), yielding -40000 kJ/mol.

Mindmap

Keywords

💡Enthalpy

Enthalpy is a thermodynamic property of a system that is often associated with the heat content of the system. In the context of the video, enthalpy is used to describe the heat change during the combustion of methane, which is a key concept in understanding the energy released in the process. The script discusses calculating the enthalpy of combustion by measuring the temperature change of water in a calorimeter, a device used for measuring heat changes.

💡Calorimeter

A calorimeter is an instrument used for measuring the amount of heat absorbed or released by a system, such as during a chemical reaction. In the video, a calorimeter is used to measure the temperature change of water when methane is burned, allowing the calculation of the enthalpy change. The script mentions a specific type of calorimeter, the bomb calorimeter, which is designed to contain explosions and measure the heat released.

💡Combustion

Combustion refers to a chemical reaction between a fuel and an oxidant, usually oxygen, that produces heat and light. In the video, the combustion of methane is discussed, which is a common reaction in the study of thermodynamics. The script describes how the combustion of 8 grams of methane leads to a temperature increase in the calorimeter, which is then used to calculate the enthalpy of combustion.

💡Temperature Change

Temperature change, often denoted as ΔT, is the difference between the final and initial temperatures of a system. The video script uses the temperature change of water in a calorimeter to calculate the heat absorbed during the combustion of methane. The script provides specific temperature values before and after the reaction to illustrate this concept.

💡Heat Capacity

Heat capacity is a property of matter that indicates the amount of heat required to change the temperature of a substance by a given amount. In the video, the heat capacity of water is given as 4.2 Joules per gram per degree Celsius, which is used in the calculation of the heat absorbed by the water during the combustion process.

💡Joule

The joule is the SI unit of energy, work, or amount of heat. In the script, joules are used to quantify the heat absorbed by the water in the calorimeter and the enthalpy change during the combustion of methane. The video provides calculations in kilojoules, a larger unit of energy, to express these values.

💡Molar Heat of Combustion

The molar heat of combustion is the amount of heat released when one mole of a substance is burned. The video script calculates the enthalpy change per mole of methane burned by dividing the total heat released by the number of moles of methane. This value is crucial for understanding the energy content of fuels.

💡Mole

A mole is a unit of measurement used in chemistry to express amounts of a chemical substance. It represents a collection of particles, specifically Avogadro's number of entities (approximately 6.022 × 10^23). The video uses the concept of moles to calculate the molar heat of combustion, which is the heat released per mole of methane during combustion.

💡Specific Heat Capacity

Specific heat capacity, often denoted as 'c', is the amount of heat required to raise the temperature of one gram of a substance by one degree Celsius. The video mentions the specific heat capacity of water as 4.2 J/g°C, which is essential for calculating the heat absorbed by the water in the calorimeter.

💡Thermodynamics

Thermodynamics is the branch of physics that deals with heat and temperature and their relation to energy and work. The video is centered around thermodynamics, specifically the calculation of enthalpy changes during chemical reactions. The script provides a practical example of how thermodynamic principles are applied to measure and calculate energy changes.

Highlights

Introduction to calculating enthalpy using a calorimeter.

Discussion of the first problem involving the combustion of 8 grams of methane.

The calorimeter's temperature rise from 25.5°C to 95°C due to the combustion.

Calculation of the temperature change (ΔT) in the calorimeter.

Details on the 4-liter water in the calorimeter and its specific heat capacity.

Assumption of the calorimeter's heat capacity as zero.

Formula for calculating reaction enthalpy using the heat lost by the water.

Calculation of the heat absorbed by the water (Q_water).

Determination of the reaction enthalpy by subtracting the heat absorbed by the water.

Conversion of the reaction enthalpy to kilojoules.

Calculation of the moles of methane (CH4) burned.

Final calculation of the enthalpy of combustion per mole of methane.

Introduction to the second problem involving the reaction of nickel with CuSO4 solution.

Temperature increase of the solution due to the reaction.

Details on the heat required to raise the temperature of the solution by 1°C.

Calculation of the reaction enthalpy under standard conditions.

Use of the heat capacity of the solution (C_solution) in calculations.

Assumption of the calorimeter's heat capacity as zero for the second problem.

Final calculation of the reaction enthalpy for the nickel and CuSO4 reaction.

Conclusion and summary of the enthalpy calculations for both problems.