Final answer:
The unknown value in the equation M = dRT / P is M. This comes from a rearranged form of the ideal gas law, which relates pressure, volume, temperature, and the number of moles of a gas, with the addition of density standing in for m/V.
Step-by-step explanation:
The student has asked to identify the unknown value in the given equation M = dRT / P. This equation is a derivative of the ideal gas law, which is PV = nRT, where P is pressure, V is volume, n is the amount of gas in moles, T is the temperature in Kelvin, and R is the ideal gas constant. Because m/V is the density d of a substance, we can replace m/V by d in the original equation. So, in the equation M = dRT / P, M is the only variable left on one side of the equation, making it the unknown value the student is seeking.
We can find the unknown M if the values of density d, the ideal gas constant R, temperature T, and pressure P are known. Rearranging the equation to solve for M gives us M = dRT / P. This shows that M is directly proportional to the density, temperature, and ideal gas constant, and inversely proportional to the pressure.