Two vessels A and B are connected via stopcock. The vessel A is filled with a gas at a certain pressure. The entire assembly is immersed in water and is allowed to come to thermal equilibrium with water. After opening the stopcock the gas from vessel A expands into vessel B and no change in temperature is observed in the thermometer. Which of the following statement is true ?
The pressure in the vessel B before opening the stopcock is zero
The question involves a system of two vessels, A and B, connected by a stopcock and immersed in a water bath. The key point to note is that the system comes to thermal equilibrium with the water before the stopcock is opened.
Let's analyze the given options:
- The expansion of gas occurs when the stopcock is opened, allowing the gas from vessel A to move into vessel B.
- Since the entire assembly is in thermal equilibrium with the surrounding water, no temperature change is observed in the thermometer.
Analyzing the options:
- dw \neq 0: This would imply work is done during expansion. Typically, when expansion is free (no external pressure), no work is done, hence dw = 0.
- The pressure in the vessel B before opening the stopcock is zero: Vessel B is initially at vacuum or negligible pressure until gas enters, hence this is a plausible statement.
- dU \neq 0: Refers to the change in internal energy. Since there is no temperature change, there is also no change in internal energy (dU = 0).
- dq \neq 0: Refers to a change in heat energy. In thermal equilibrium with no temperature change, dq = 0.
Conclusion: The correct statement is: The pressure in the vessel B before opening the stopcock is zero. This corresponds to the condition that vessel B initially has no gas or negligible pressure, allowing gas from vessel A to occupy it when the stopcock is opened.
Similar Questions
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Consider the above reaction, what mass of $CaCl_2$ will be formed if 250 mL of 0.76 M HCl reacts with 1000 g of $CaCO_3$ ?
(Given: Molar mass of Ca, C, O, H and Cl are 40, 12, 16, 1 and 35.5 g $mol^{-1}$, respectively)- According to Bohr's model of hydrogen atom, which of the following statement is incorrect?
Which of the following graphs correctly represents the plot of $K_H$ at 1 bar for gases in water versus temperature?
If equal volumes of $AB_2$ and $XY$ (both are salts) aqueous solutions are mixed, which of the following combination will give a precipitate of $AY_2$ at 300 K ?
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The couple $QH_2/Q$ represents quinhydrone electrode, the half cell reaction is given below :
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Important Questions from Physical Chemistry
$CaCO_3(s) + 2HCl(aq) \rightarrow CaCl_2(aq) + CO_2(g) + H_2O(l)$
Consider the above reaction, what mass of $CaCl_2$ will be formed if 250 mL of 0.76 M HCl reacts with 1000 g of $CaCO_3$ ?
(Given: Molar mass of Ca, C, O, H and Cl are 40, 12, 16, 1 and 35.5 g $mol^{-1}$, respectively)- According to Bohr's model of hydrogen atom, which of the following statement is incorrect?
Which of the following graphs correctly represents the plot of $K_H$ at 1 bar for gases in water versus temperature?
If equal volumes of $AB_2$ and $XY$ (both are salts) aqueous solutions are mixed, which of the following combination will give a precipitate of $AY_2$ at 300 K ?
(Given $K_{sp}$ (at 300 K) for $AY_2=5.2 \times 10^{-7}$)On complete combustion 1.0 g of an organic compound (X) gave 1.46 g of $CO_2$ and 0.567 g of $H_2O$. The empirical formula mass of compound (X) is ________ g.
(Given molar mass in g $mol^{-1}$ C: 12, H: 1, O: 16)
