If a fine hole is made in the vessel then which gas escapes out more rapidly? At a given volume and temperdtiife the Pressure of a gas. Which of the following methods will enable the volume of an ideal gas to be made four times greater? Consider absolute temperature. At absolute zero temperatrue , the Kinetic energy of the molecules:. Physics Most Viewed Questions. The phase difference between displacement and acceleration of a particle in a simple harmonic motion is: NEET Oscillations.
The energy equivalent of 0. Two cylinders A and B of equal capacity are connected to each other via a stop clock. A contains an ideal gas at standard temperature and pressure. B is completely evacuated. The entire system is thermally insulated. The stop cock is suddenly opened. A screw gauge has least count of 0.
For which one of the following, Bohr model is not valid? NEET Atoms. Ideal gas behaviour and the gas laws. Introduction — t he kinetic particle model of an ideal gas.
The advanced kinetic theory of gases is founded on the following six fundamental postulates: Gases are composed of minute discrete particles usually molecules.
The bombardment of the container walls by the particles causes the phenomenon we call pressure i. The greater the force of collision and the more frequent the collisions the greater the gas pressure exerted on the container surface. The collisions are perfectly elastic i. At relatively low pressures the average distance between particles is large compared to the diameter of the particles and therefore the inter—molecular forces between the particles is negligible. The average kinetic energy of the particles is directly proportional to their absolute temperature on the Kelvin scale K i.
KE J T K This means if you heat up a gas the average kinetic energy of the particles increases, therefore the average speed increases too. The Kelvin scale of temperature is explained below. When a gas behaves according to this model, the gas laws described in sections 4a to 4e are obeyed.
However in real gases things are not so simple and this non—ideal behaviour is discussed in section 5. The Kelvin Scale of Temperature. In the past lots of measurements have been made to investigate how i the pressure and volume of a given mass of vary at constant temperature and how ii the pressure and volume gas of a fixed mass of gas varies with temperature see the two graphs left and right. This resulted in the formulation of the laws of gases described in the next section 4a.
However, before this, if you look at these two graphs of gas behaviour when changing pressure or volume with temperature, one thing becomes clear, when the graph lines are extrapolated back to the x axis they give a value of — o C. This gave rise to the idea that there was a minimum possible temperature of — o C and further experimentation has confirmed this time and time again.
At — o C all substances are solid and in terms of the kinetic particle theory of matter, at — o C the particles have virtually no motion i. Therefore as well as the established Celsius scale centigrade scale , a new temperature scale was proposed in which the lowest value was 0 known as absolute zero rather than — This is called the Kelvin scale of temperature or the absolute temperature scale , denoted by the unit K.
Incidentally you don't say degrees Kelvin like you say degrees Celsius, you just say Kelvin. The Kelvin temperature scale was also designed so that a 1 K temperature change or interval, exactly equals 1 o C Celsius change or interval.
Therefore you can easily convert between the two temperature scale by a simple calculation. Some examples are worked out below and a practice in reading a Celsius thermometer, which is what you use in the school or college laboratory! It seems a bit weird to say you body has a temperature of , which is why it is always important to state the units too! The particle model of a gas - motion and gas pressure. All particles have mass and their movement gives them kinetic energy and momentum.
The particles in a gas are in constant random motion - random direction, variety of velocities and kinetic energies. When the fast moving gas particles collide with a surface, their millions of impacts create a force that we measure as gas pressure - the total force of impacts per unit area.
The particles collide with the container surface completely at random and impact at every angle, BUT, the effect is to create a net force at right angles to the surface - gas pressure! The greater the number of collisions per unit area of surface, the greater the pressure, assuming the gas volume and temperature are kept constant.
If the temperature is kept constant and the volume increased, the impacts are more spread out and less frequent per unit area, so the gas pressure decreases. Conversely, if a gas is compressed into a smaller volume at constant temperature, the number of impacts per unit area increases, so the pressure increases.
From measurements of volumes and pressure of gases at constant pressure, a numerical inverse law can be formulated - Boyle's law. You can connect two pressure and two volumes by the simple equation. Examples of simple gas calculations. More on gas pressure and volume calculations. Boyle's Law for volume and gas pressure. The particle theory of gas pressure was explained in Part 1 so this section concentrates on the gas law calculations involving pressure and volume.
Boyle's Law states that for given mass of gas at a constant temperature o C or K , the product of the pressure multiplied by the volume is a constant. At lower temperatures the volume and pressure values are lower see next section. You can use any volume or pressure units you like as long as both p's and both V's have the same units. Using particle theory and simple arithmetical values to explain Boyles Law.
If a gas is compressed to half its original volume the concentration or density of the gas is doubled. Therefore there will be twice as many collisions with the surface causing twice the impact effect i.
If the volume of a gas is increased by a factor of three, the concentration is reduced by the same factor, so the chance of particle collision with the container walls is similarly reduced, so the pressure decreases by a factor of three. Gases e. Because the internal pressure in the cylinder is so much greater than the external pressure, on fitting a valve, a large volume of gas can be released to flow slowly under controlled conditions for a patients respiration.
Examples of Boyle's Law calculations constant temperature assumed Ex. Q4a 1 cm 3 of air at a pressure of kPa in a bicycle pump is compressed to a volume of cm 3. What is the pressure of the compressed air in the pump?
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