The mass of substance m is the size equal to the work of molar mass of substance M and amount of substance n. The formula of calculation becomes complicated if these indicators have to be counted through other known.
It is required to you
- Table of density, calculator.
Instruction
1. If in a task the following data are known to you: p pressure, v volume, T temperature in degrees of a thermodynamic scale of Calvin (K) and the molar mass of substance M, then the mass of this substance m find on a formula: p*v=m/M*R*T, having expressed from it m. At you the following formula has to turn out: m=M*p*v / (R*T). R - it is the universal gas constant equal of 8.314 J / (mol*k).
2. Solve the offered task. Task: Find the mass of substance m if p=10 of Pa, v=2 of cubic meter, T=30 K, M=24 kg/mol. Substitute all known values in the last formula and count (the answer: the mass of substance m is approximately equal to 1.9 kg).
3. It is possible to find the mass of substance m also if only the volume of v and substance are known to you. The following formula allows to make it: m=ro*v where ro is the density of substance (mass of its single volume), is measured in kg / cubic meter. To find density of the substance it is possible to find in the table of density.
4. Now solve the offered task: find the mass of aluminum m if cubic meter v=2. To solve this problem, find aluminum density in the table of density (ro (aluminum) =2.7*10^3 kg / cubic meter) and count value of mass of aluminum m on already known formula. As a result you receive the answer that the mass of aluminum m is equal to 5400 kg).
5. Whether it is necessary to know in general the volume of a body and density of substance of which it is made to find its weight? For example, it is known that the volume of brass is equal to aluminum volume, but the mass of brass is more than the weight of aluminum. It is possible to assume that at brass and aluminum different density. Conclusion: to find body weight, it is necessary to know its volume and mass of unit of volume. The mass of unit of volume is and there is substance ro density.