There are five parameters in ideal gas law equation (PV = nRT). When you know four parameters, you can find the unknown parameter in the equation. Ideal gas law questions are asked frequently in physical chemistry papers and air problems.
You can use following calculator to calculate unknown parameter in PV = nRT equation. Keep empty unknown parameter field.
Parameters of equation are given below with their units.
additional data: R = 8.314 J mol-1 K-1, Molar mass of gas = 28 g mol-1
Temperature was given in celsius. Convert it to Kelvin as below..
Temperature = 27 + 273 = 300 K
Drawing a figure is a good way to illustrate the question. Write down all the data provided with units.
We know the date of pressure, volume and temperature. Then, we can substitute those values in PV = nRT equation to find the amount.
Above question was a straightforward one. now we are going to discuss little bit difficult question.
If above tank is connected with another empty tank (B) with same volume through a short pipeline, what is the pressure of the overall system when system is still at 300K?
The gas amount is now distributed in two tanks.
Now, we can apply ideal gas law equation to find the pressure (P') of the system.
10g of calcium carbonate crystals are heated to a high temperature in a closed container until all calcium carbonate decomposes to calcium oxide and carbon dioxide gas. After decomposition was completed, heating was stopped and container was put to reach to the room temperature. Initially, there were not gases inside the container. After heating the calcium carbonate crystals, remaining solid was weighed and it was 4g. If volume of container is 8314 cm3, calculate the pressure inside the container at room temperature (250C).
From given date, we know the volume and temperature of PV = nRT. Therefore, we need to find out amount (n) before finding the pressure of the container.
For that, we can use chemical equation and weight of calcium carbonate.
Decomposed CaCO3 amount = produced CO2 amount
Now, we know the gas amount (n) and can apply the values in PV = nRT equation.
Question:There are two gases (A and B) in a closed container (1 m3) at 1270C. Amount of gases of A and B are 10 mol and 20 mol respectively. Calculate followings.
We can solve this question in two ways.
Total pressure in the system is given by the summation of partial pressures of both gases.
Because, we assume that A and B gases behave as ideal gases. Therefore, we can apply ideal gas law for the overall system considering there are total of 30 mol in the system.
In this method, we apply ideal gas law in two occasions for A and B gases to find partial pressures of A and B gases.
Now, we can add partial pressures of A and B gases to find total pressure.
There are two gases (A and B) which react with each other as below.
A + B → C
In a specified industry, a mixture of C and B gases is required and above reaction is proposed to use to get that mixture.
Both gases are stored in two separate containers which have same volume. A gas is at 100 kPa and B gas is at 200kPa. Both containers were heated separately to 2270C and then mixed with each other to react. Containers were kept at 2270C continuously until reaction is completed. Volume of one container is 8.314 m3.
First two parts of this question is very easy and we have already did those kind of questions earlier in this tutorial. For first two sections, pressure, volume and temperature values are given for each gas and we just need to find the amount of each gas by applying PV = nRT.
Now, we know the initial amount of A and B gases. So, we should find now the reacting amount of A and B gas as below.
Answer for part 3,
In the end of the reaction, only B and C gases are remaining.Total gas amount after the reaction = 200 mol + 200 mol = 400 mol
Because temperature is maintained at 2270C (500K) and total gases amount, volume of containers are known, we can find the final pressure of the container after the reaction.
Here, you can try some MCQ questions relavant to PV = nRT
An ideal gas is filled to a constant volume container (1 dm3) at 270C temperature. When internal pressure is reached upto 1 bar, filling is stoped and container is sealed. How much (mol) gas is fiiled to the container.