Question

1. Using what you know about the of molecules in a liquid, explain alcohol moves down a cooled thermometer.

2. The animation shows that the molecules spread out slightly when heated. Do you think the thermometer would work as well if the tube of red liquid were wider? Why or why not? Use evidence to support your answer.

Answer 1

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Answer 2

Alcohol moves down a cooled thermometer due to a decrease in kinetic energy among its molecules, causing a contraction in volume due to reduced thermal agitation.Final Answer: A wider tube for the red liquid in the thermometer might impact its functionality as the expansion and contraction of the liquid could become less noticeable, affecting the sensitivity of the thermometer.

Step-by-step explanation:

Alcohol, like any liquid, consists of molecules in constant motion. When cooled, the molecules lose kinetic energy, reducing their movement. As temperature drops, molecular motion decreases, causing a contraction in volume. This contraction leads to a decrease in pressure inside the thermometer, prompting the liquid to move down to an area of lower pressure.

In a wider tube, the expansion and contraction of the red liquid may be less conspicuous. The change in volume due to temperature variation might not create a significant difference in the liquid's level, potentially reducing the sensitivity of the thermometer. For instance, if the liquid expands by 1mm in a narrow tube, the same temperature change might only cause a negligible rise in a wider tube, compromising the thermometer's ability to detect subtle temperature changes accurately.

To quantify this, consider the coefficient of thermal expansion (α) and the change in volume (ΔV) of the liquid. For instance, if the liquid's original volume is V and its coefficient of expansion is α, the change in volume due to temperature change (ΔT) is calculated as ΔV = V * α * ΔT. This change in volume affects the liquid's level in the thermometer. In a wider tube, the same change in volume might result in a smaller change in liquid level compared to a narrower tube due to the difference in cross-sectional area.

Therefore, a narrower tube allows for a more noticeable change in liquid level, enhancing the thermometer's sensitivity to temperature fluctuations. A wider tube could compromise this sensitivity, affecting the accuracy of temperature readings due to a reduced observable change in the liquid's volume with changing temperatures.