Daily Online News

If you trap a sample of air and measure its volume at different pressures (constant temperature), then you can determine a relation between volume and pressure. If you do this experiment, you will find that as the pressure of a gas sample increases, its volume decreases. In other words, the volume of a gas sample at constant temperature is inversely proportional to its pressure. The product of the pressure multiplied by the volume is a constant: PV = k or V = k/P or P = k/V where P is pressure, V is volume, k is a constant, and the temperature and quantity of gas are held constant. This relationship is called Boyle's Law, after Robert Boyle, who discovered it in 1660. Worked Example Problem The sections on the General Properties of Gases and Ideal Gas Law Problems may also be helpful when attempting to work Boyle's Law problems. Problem A sample of helium gas at 25°C is compressed from 200 cm3 to 0.240 cm3. Its pressure is now 3.00 cm Hg. What was the original pressure of the...

Chemistry Lab Instructions You can use common chemistry lab chemicals and equipment to prepare several gases. A conical flask, thistle funnel, delivery tube, pneumatic trough, and beehive are useful items to have on hand. Please make sure you are familiar with the use and functioning of the laboratory equipment you use, are aware of the characteristics of the substances (toxicity, flammability, explosivity, etc.), and take proper safety precautions. Use a ventilation hood (fume cupboard) and keep flammable gases away from heat or flame. I've tried to be as accurate as possible in my instructions, but you use them at your own risk. For convenience, I've listed the gases in alphabetical order. If you would like to add a procedure or have comments about any of these procedures, please feel free to e-mail me. Gas Reagents Method Collection Reaction Ammonia Gently heat a mixture of ammonium chloride and calcium hydroxide in water. NH3 Ammonium chloride Calcium hydroxide Upward displ...

Gases : Examine the properties of real and ideal gases. Perform calculations using the Ideal Gas Law, Dalton's Law, Graham's Law, and Van der Waals Equation. Learn to prepare gases in the lab. General Properties of Gases All pure substances display similar behavior in the gas phase. At 0° C and 1 atmosphere of pressure, one mole of every gas occupies about 22.4 liters of volume. Molar volumes of solids and liquids, on the other hand, vary greatly from one substance to another. In a gas at 1 atmosphere, the molecules are approximately 10 diameters apart. Unlike liquids or solids, gases occupy their containers uniformly and completely. Because molecules in a gas are far apart, it is easier to compress a gas than it is to compress a liquid. In general, doubling the pressure of a gas reduces its volume to about half of its previous value. Doubling the mass of gas in a closed container doubles its pressure. Increasing the temperature of a gas enclosed in a container increases its pr...