Question

You carry out a chemical reaction in a calorimeter to determine the heat change for the reaction. Identify the system and surroundings.

Short answer

The chemical reaction taking place inside the calorimeter is the system, and the calorimeter itself and its external environment are the surroundings.

Step-by-step solution

Identification of the System

In calorimetry, the reaction being studied is identified as the system. Therefore, in this exercise, the system is the chemical reaction occurring inside the calorimeter.

Identification of the Surroundings

Everything outside the chemical reaction but still capable of exchanging energy with it is considered the surroundings. Hence, in this case, the surroundings consist of the calorimeter and the external environment to it, because both can absorb or release energy during the reaction

Key concepts

Chemical Reaction

Chemical reactions are fascinating processes where substances, known as reactants, are transformed into different substances called products. During a chemical reaction, bonds between atoms are broken and new bonds form, resulting in a change in the composition of matter. This transformation can occur naturally or be induced in a controlled environment, such as a laboratory setting.
In a calorimeter, a chemical reaction takes place where the reactants interact and change at a molecular level. Depending on factors such as temperature, pressure, and catalysts, the speed and outcome of the reaction can vary. Measuring temperature changes during the reaction helps us understand how much energy is released or absorbed, providing vital information about the reaction's nature.

Heat Change

In calorimetry, heat change is a key focus as it gives insights into the energy dynamics of chemical reactions. Heat change is the difference in thermal energy between the products and reactants during a reaction. It can be exothermic, where energy is released, or endothermic, where energy is absorbed.
To quantify the heat change, scientists use calorimetry, which involves measuring the temperature difference before and after the reaction. This temperature change, along with the calorimeter's known properties, allows calculation of the heat exchanged using the formula \ : Q = mc\Delta T \ :

• Q = heat exchanged (in joules)
• m = mass of the substance (in grams)
• c = specific heat capacity (in J/g°C)
• \( \Delta T \) = change in temperature (in °C)

Understanding the heat change reveals whether a reaction releases or absorbs energy, which is crucial in fields like chemistry, biology, and engineering.

System and Surroundings

In the study of chemical reactions, it's crucial to understand the concepts of system and surroundings. The system refers to the part of the universe we are studying - in our case, the chemical reaction happening inside a calorimeter.
The surroundings include everything outside the system that can still interact with it, either by gaining or losing energy. This can involve the components of the calorimeter itself and the immediate external environment capable of energy exchange.

• System: The specific part of the universe under investigation, i.e., the chemical reaction inside the calorimeter.
• Surroundings: Includes everything that can absorb or release energy affecting the reaction, like the calorimeter and its environment.

This differentiation makes it easier to analyze energy transactions, ensuring accurate measurements in calorimetry studies. Understanding what constitutes the system and its surroundings helps students properly engage with concepts of energy transfer, which play a vital role whenever thermal processes are involved.