what law allows us to calculate a change in volume when the temperature changes , but the pressure is held constant
Charles' Law.
(V1/T1) = (V2/T2)
The law that allows us to calculate a change in volume when the temperature changes, but the pressure is held constant, is called Charles's Law. Charles's Law states that when the pressure of a gas is constant, the volume is directly proportional to the temperature.
Mathematically, Charles's Law can be expressed as:
V₁ / T₁ = V₂ / T₂
where V₁ and T₁ are the initial volume and temperature, and V₂ and T₂ are the final volume and temperature.
To calculate a change in volume under constant pressure, you need to know the initial and final temperatures and volumes. Rearranging the equation, you can solve for the final volume (V₂) by multiplying the initial volume (V₁) by the final temperature (T₂) and dividing it by the initial temperature (T₁):
V₂ = (V₁ * T₂) / T₁
In this formula, the temperatures must be in Kelvin (K) since temperature scale conversions are not needed when using this law.
It is important to note that this law assumes ideal gas behavior and that other factors, such as pressure changes or the presence of non-ideal gases, may affect the accuracy of the calculation.