Change in Level of Liquid in Container

What happens when liquid is heated in a container?

Table of Contents:

• Aim

• Apparatus Required

• Theory

• Procedure

• Observations

• Calculation

• Result

• Interpretation

• Precautions

• Source of Error

• Lab Manual Questions

• Viva Questions

• Practical Based Questions

Aim

To note the modification in level of liquid in an exceedingly instrumentation on heating and interpret the observations.

Apparatus Required

• A Round Bottom Glass Flask  with Volume Indicator

• Liquid (Having Boiling Point Above 100 c

• Water Bath 

• Heating Arrangement

• Thermometer with Hanging Arrangement

Theory

1. Real cubical enlargement of a liquid = Apparent cubical enlargement of the liquid + Cubical enlargement of the vessel. 

2. $\gamma_{r}=\gamma_{a}+\gamma_{g}$

Diagram

liquid in an exceedingly instrumentation on heating 

Procedure

• Clean and dry the lowest of the glass flask. 

• Fill it with the experimental liquid up to a identified mark A to possess a known volume of liquid. Place the flask in water tub unbroken on a rack stand, beneath that some heating arrangement (gas burner) is fitted.

• Suspend a measuring system within the liquid with its bulb in the middle of the flask

• Note and record  the minimum thermometer count.

• Note initial temperature of the liquid is 1 °C. 

• Start heating the liquid and keep an eye on the A mark, you will see the liquid level drop.

• When the water in the water bath begins to boil, the temperature of the liquid in the flask will stabilize and the liquid level will drop to the B mark.

• Note that the temperature of the liquid  (t 2 °C) and the position of the volume of the mark  between A and B give a cubic expansion of the glass bulb).

• Continue to heat the liquid through a water bath. The liquid level rises because  the liquid is now beginning to expand. The level reaches A and continues to rise. The level stabilizes at the C mark. 

• Note the position of mark C. (The volume between B and C indicates a true cubic expansion of the liquid.)

Record Your Observations as Given Below.

Observations

Least count of thermometer = ………..°C

Initial (room) temperature of liquid(t1) = ………………°C.

Final (bath) temperature of liquid (t2) = …………..°C.

Table for position of marks.

Calculations

• The difference in the position of the A and B marks gives the cubic expansion $V_{AB}$ of the container. 

• Find the difference in the positions of the B and C marks. This gives the true cubic expansion $V_{BC}$ of the liquid. 

• Find the difference in the positions of marks A and C. This gives an apparent cubic expansion $V_{AC}$ of the liquid.

Result 

The actual cubic dimension of the liquid is greater than the apparent cubic dimension. The difference becomes smaller if the container is made of a material that has a very small coefficient of cubic expansion

Interpretation

The liquid level drops due to the initial thermal expansion of the container. 

Precautions

1. The boiling point of the liquid must be higher than that of the bath liquid (water). 

2. The heating of the liquid must be even during a bath.

3. Observations should be made when the temperature stabilizes. 

Sources of Error

1. The heating of the liquid may not be uniform. 

2. The temperature may not be stable

Lab manual questions 

1. Apparent expansion of a liquid depends upon?

Ans: The real expansion of liquid and fluid will be $\Delta V_{1}=\gamma_{1}.\Delta T$  T and $\Delta V_{\text{fluid}}=\gamma_{\text{fluid}}.\Delta T$ ,respectively. Since apparent enlargement could be distinction of those two. Hence 

$\Delta V_{\text{apparent}}=\left ( \gamma_{1}-\gamma_{\text{vessel}} \right )\cdot \Delta T$

Thus, apparent enlargement depends upon the character of the liquid, the nature of the vessel, and also the temperature rise.

2. The apparent change in volume of a liquid per 100°C is 8%. Then coefficient of a apparent expansion of liquid ?

Ans:  8 × 10 - 4 °C

3. What are the factors that will affect the thermal expansion in liquids?

Ans: The amount by which it expands depends on three factors - its original length, the temperature change, and the thermal properties of the metal itself.

4. What are the applications of thermal expansion of liquids?

Ans: When the bulb of thermometer is kept in contact with a hot body the mercury expands and the level of mercury rises in the capillary tube. This is a crucial application of thermal enlargement in liquids.

5. Identify one problem caused by expansion?

Ans: Bridges expand in the summer heat due to excessive temperature rises, necessitating special joints to prevent them from bending out of shape.

6. How does thermal expansion affect sea level rise?

Ans: The warming of the earth is fundamentally due to the accumulation of heat-absorbing greenhouse gases. Oceans absorb extra than ninety percentage of this heat. Because of this heat absorption, the temperature of the oceans rises and water expands.

Viva Questions

1. Define real cubical expansion of a liquid?

Ans. The actual increase in volume of a liquid (taking into account the expansion of the container) is called the actual cubic expansion of the liquid.

2. Define apparent cubical ?

Ans. The observed increase in the volume of a liquid (without expansion of the container) is called the apparent cubic expansion of the liquid.

3. Give relation between $\gamma_{r}$ and $\gamma_{a}$ ?

Ans. The relation is, $\gamma_{r}=\gamma_{a}+\gamma_{g}$

Conclusion

The liquid level drops due to the initial thermal expansion of the container. The boiling point of the liquid must be higher than that of the bath liquid (water). The liquid must be heated evenly throughout the bath. Observations should be made when the temperature stabilizes.