Question

A student places a thermometer in hot water during a lab and the column of fluid inside the thermometer rises to 90 ° Celsius. What causes the change in the thermometers' readings?
Responses

A Entropy causes fluid in the thermometer to crystalize and expand.Entropy causes fluid in the thermometer to crystalize and expand.

B The hot water acts as a catalyst causing a chemical reaction in the thermometer.The hot water acts as a catalyst causing a chemical reaction in the thermometer.

C Radiation from the water causes fluid in the thermometer's bulb to push the fluid in the column higher .Radiation from the water causes fluid in the thermometer's bulb to push the fluid in the column higher .

D The heat of the water causes molecules in the thermometer's fluid to move faster, spread apart, and rise in the thermometer's column

Answer 1

D

The heat from the water is transferred to the thermometer (mostly by conduction), increasing the thermal energy of the liquid’s molecules so they move faster and on average occupy more space (thermal expansion). Because the liquid’s density decreases and the bulb holds a fixed cross-sectional area, the expanded liquid rises up the column until thermal equilibrium is reached.