What is assumed to be constant when using the combined gas law?
A. pressure
B. number of moles
C. volume and moles of gas
D. pressure and temperature
Answer (2)
When using the combined gas law, the number of moles of gas is assumed to be constant. The correct answer is B. number of moles. This allows for accurate predictions of how pressure, volume, and temperature interact without changing the quantity of gas.
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The combined gas law relates pressure, volume, and temperature of a gas.
The equation for the combined gas law is T 1 P 1 V 1 = T 2 P 2 V 2 .
The number of moles and the ideal gas constant are assumed to be constant.
Therefore, the number of moles is assumed to be constant when using the combined gas law. number of moles
Explanation
Understanding the Combined Gas Law The combined gas law relates pressure (P), volume (V), and temperature (T) of a gas. The equation for the combined gas law is:
The Equation T 1 P 1 V 1 = T 2 P 2 V 2
Assumptions of the Law This law is derived from the ideal gas law, P V = n RT , where n is the number of moles and R is the ideal gas constant. In the combined gas law, the number of moles ( n ) and the ideal gas constant ( R ) are assumed to be constant.
Conclusion Therefore, when using the combined gas law, the number of moles is assumed to be constant.
Examples
The combined gas law is useful in scenarios where you need to calculate the changes in pressure, volume, or temperature of a gas when one or more of these variables change, assuming the amount of gas (moles) remains constant. For example, if you have a balloon with a certain volume at room temperature and normal atmospheric pressure, and you want to predict the new volume if you take the balloon to a higher altitude where the temperature and pressure are different, you can use the combined gas law. By keeping the number of moles constant, we can accurately predict the behavior of gases under varying conditions, which is crucial in many engineering and scientific applications.
