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I HAVE FOLLOWING DOUBTS.. 1)TWO SPHERICAL FLASKS HAVING A VOLUME V=1L EACH CONTAINING AIR ARE CONNECTED BY A TUBE OF DIAMETER D=6MM AND LENGHT L=1M..A SMALL DROPLET OF MERCURY CONTAINED IN THE TUBE IS AT THE MIDDLE AT 273K ..BY WHT DISTANCE DO MERCURY DROPLETS MOVE IF FLASK 1 IS HEATED BY 2'C AND FLASK 2 IS COOLED BY 2'C.. 2)A NON CONDUCTING CYLINDRICAL VESSEL OF LENGHT 3L IS PLACED HORIZONTAL;LY AND IS DIVIDED INTO 3 PARTS BY 2 EASILY MOVING PISTONS HAVIN LOW THERMAL CONDUCTIVITY ..THESE PARTS CONTAIN H2 HE AND CO2 GA AT INITIAL TEMP 372'C , -15'C , 157'C RESPECTIVELY..IF INITIAL LENGHT AND PRESSURE OF EACH AARE L AND P RESPECTIVELY , CALCULATE FINAL PRESSURE AND LENGHT OF EACH PART..(GIVEN Y FOR CO2 =1.4) 3)A BAROMETER IS FAULTY,,WHEN TRUE BAROMETER REAS 73 AND 75 CM OF HG, THE FAULTY READS 69 AND 70CM.. WHAT IS THE TOTAL LENGHT OF BAROMETER TUBE? WHAT IS THE FAULTY READING WHEN TRUE READING IS 74CM?

akhil samir killawala , 16 Years ago
Grade 11
anser 1 Answers
Askiitians Tutor Team

Let's break down your questions one by one, starting with the first scenario involving the two spherical flasks connected by a tube. This situation can be analyzed using the principles of gas laws and the concept of thermal expansion.

Movement of Mercury Droplet in Connected Flasks

In your setup, we have two flasks, each with a volume of 1 liter, connected by a tube. When Flask 1 is heated by 2°C and Flask 2 is cooled by 2°C, the change in temperature affects the pressure of the gases inside the flasks, which in turn will cause the mercury droplet to move.

Understanding Gas Behavior

According to Gay-Lussac's Law, the pressure of a gas is directly proportional to its absolute temperature when the volume is constant. The formula can be expressed as:

  • P1/T1 = P2/T2

Where P is pressure and T is temperature in Kelvin. Let's convert the temperature changes:

  • Initial temperature of Flask 1: 273 K + 2 K = 275 K
  • Initial temperature of Flask 2: 273 K - 2 K = 271 K

Calculating Pressure Changes

Assuming the initial pressure in both flasks is the same (P), we can set up the equations:

  • For Flask 1: P1/273 = P'/275
  • For Flask 2: P2/273 = P'/271

From these equations, we can derive the new pressures:

  • P'1 = P * (275/273)
  • P'2 = P * (271/273)

Pressure Difference and Mercury Movement

The difference in pressure between the two flasks will cause the mercury to move. The pressure difference (ΔP) can be calculated as:

  • ΔP = P'1 - P'2 = P * [(275/273) - (271/273)]

This pressure difference will push the mercury droplet towards the cooler flask. The distance the mercury moves can be calculated using the hydrostatic pressure equation:

  • Δh = ΔP / (ρg)

Where ρ is the density of mercury and g is the acceleration due to gravity. You can plug in the values to find the exact distance.

Pressure and Length in a Non-Conducting Cylindrical Vessel

Now, let’s move on to the second question regarding the non-conducting cylindrical vessel divided into three parts. Here, we will apply the ideal gas law and the concept of thermal equilibrium.

Initial Conditions

We have three gases: H2, He, and CO2 at different temperatures. The initial lengths of the gas columns are equal, and the initial pressure is P for each. The gases will expand or contract based on their temperatures.

Using the Ideal Gas Law

The ideal gas law states:

  • PV = nRT

Since the volume is constant and the number of moles (n) remains unchanged, we can express the final conditions in terms of the initial conditions and temperature changes:

  • P1/T1 = P2/T2

For each gas, we can calculate the final pressure after reaching thermal equilibrium. The final pressure for CO2 can be calculated using its specific heat ratio (γ = 1.4) to account for its behavior under these conditions.

Final Length and Pressure Calculation

After calculating the final pressures for each gas, you can determine the final lengths based on the relationship between pressure and volume, keeping in mind that the total volume remains constant.

Faulty Barometer Analysis

Lastly, let’s address the faulty barometer. You provided readings from both the true and faulty barometers. To find the total length of the barometer tube, we can analyze the discrepancies in the readings.

Calculating the Length of the Barometer Tube

The true readings are 73 cm and 75 cm, while the faulty readings are 69 cm and 70 cm. The difference in readings can help us determine the length of the barometer tube:

  • True reading difference: 75 - 73 = 2 cm
  • Faulty reading difference: 70 - 69 = 1 cm

From this, we can establish a ratio to find the total length of the barometer tube. If we assume the faulty readings are consistently lower, we can extrapolate the total length based on the average discrepancy.

Finding the Faulty Reading for 74 cm

To find the faulty reading when the true reading is 74 cm, we can apply the same ratio derived from the previous readings. If the true reading of 73 cm corresponds to a faulty reading of 69 cm, we can set up a proportion to find the faulty reading for 74 cm.

By applying these principles and calculations, you can derive the answers to your questions. If you need further clarification on any specific part, feel free to ask!

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