Calorific Value of Ethanol (Brændværdi for sprit)

Vocabulary flashcards covering the key terms, formulas, experimental procedure, and sources of error from the physics experiment on the calorific value of ethanol.

Brændværdi

Den mængde energi eller varme, der frigives, når et brændstof eller materiale brænder helt ud, målt i enheden $\frac{\text{MJ}}{\text{kg}}$.

Purpose (Formål)

To determine how much energy can be obtained from bioethanol by calculating its calorific value.

Thermal energy formula ($E = m \cdot c \cdot \Delta T$)

The formula used to calculate the amount of energy transferred to a substance undergoing a temperature change, where $m$ is mass, $c$ is specific heat capacity (varmefylde), and $\Delta T$ is the temperature change.

Specific heat capacity ($c$ / Varmefylde)

The physical property of a substance indicating how much energy is required to change its temperature per unit of mass; accounted for separately for the can and water due to differing values.

Mass of water ($m_{\text{vand}}$)

The mass calculated by subtracting the mass of the empty can ($m_{\text{dåse}}$) from the combined mass of the can and water ($m_{\text{dåse + vand}}$).

Temperature change ($\Delta T$)

The change in temperature determined by subtracting the initial temperature from the final temperature: $\Delta T = T_{\text{efter}} - T_{\text{før}}$.

Energy absorbed by the can ($E_{\text{dåse}}$) and water ($E_{\text{vand}}$)

The separate calculations of absorbed energy: $E_{\text{dåse}} = m_{\text{dåse}} \cdot c_{\text{dåse}} \cdot \Delta T$ and $E_{\text{vand}} = m_{\text{vand}} \cdot c_{\text{vand}} \cdot \Delta T$, calculated individually due to their different heat capacities.

Closed system assumption (Fejlkilde)

A key source of error in the experiment based on the initial assumption that the spirit, water, and can constitute a closed system in which energy is conserved.

Relative deviation (Relativ afvigelse)

A measure of experimental error given by the formula $\frac{\text{Forsøgsværdi} - \text{tabelværdi}}{\text{tabelværdi}}$ ($\frac{\text{Experimental value} - \text{Reference value}}{\text{Reference value}}$).