Question

Difficulty: MediumThermal Expansion of Liquids and Anomalous Expansion of Water

A glass flask of volume 800 cm3800\text{ cm}^3 at 10C10^\circ\text{C} is completely filled with a liquid having a real volume expansivity of 5.0×104 K15.0 \times 10^{-4}\text{ K}^{-1}. If the linear expansivity of the glass is 1.0×105 K11.0 \times 10^{-5}\text{ K}^{-1}, what volume of the liquid (in cm3\text{cm}^3) will overflow when the flask and its contents are heated to 60C60^\circ\text{C}?

Answer: 18.8 cm^3

Answer

18.8 cm^3
The volume of liquid that overflows is equal to the apparent increase in volume of the liquid. The apparent volume expansivity of the liquid \(\gamma_a\) is given by \(\gamma_a = \gamma_r - \gamma_v\), where \(\gamma_r = 5.0 \times 10^{-4}\text{ K}^{-1}\) is the real expansivity of the liquid, and \(\gamma_v = 3\alpha = 3 \times 1.0 \times 10^{-5} = 0.3 \times 10^{-4}\text{ K}^{-1}\) is the volume expansivity of the glass flask. Therefore, \(\gamma_a = 5.0 \times 10^{-4} - 0.3 \times 10^{-4} = 4.7 \times 10^{-4}\text{ K}^{-1}\). The overflow volume is \(\Delta V_a = V_0 \times \gamma_a \times \Delta T = 800 \times (4.7 \times 10^{-4}) \times 50 = 18.8\text{ cm}^3\).

Step-by-Step Solution

1
Calculate the cubic expansivity of the glass flask
\(\gamma_v = 3.0 \times 10^{-5}\text{ K}^{-1} = 0.3 \times 10^{-4}\text{ K}^{-1}\)
The volume expansivity of a solid container is three times its linear expansivity (\(\gamma_v = 3\alpha\)).
2
Determine the apparent volume expansivity of the liquid
\(\gamma_a = 4.7 \times 10^{-4}\text{ K}^{-1}\)
Apparent expansivity is equal to real expansivity minus the vessel cubic expansivity (\(\gamma_a = \gamma_r - \gamma_v\)).
3
Calculate the change in temperature
\(\Delta T = 50\text{ K}\)
The temperature increases from 10C10^\circ\text{C} to 60C60^\circ\text{C}.
4
Calculate the overflow volume
\(\Delta V_a = 18.8\text{ cm}^3\)
The overflow volume is the apparent expansion of the liquid given by \(\Delta V_a = V_0 \gamma_a \Delta T\).

Key Concept

Real and apparent cubic expansivity of liquids
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