Experiment 12 The General Gas Law Name L. OBJECTIVES I. To measure the volume, t

Question

Experiment 12 The General Gas Law Name L. OBJECTIVES I. To measure the volume, temperature, and pressure of gases. 2. To apply Dalton's law to measure the pressure of a gas over water 3. To test the general gas law 4. To understand changes in the volume of a gas as the temperature and pressure are changed. HAZARDS: Bunsen bumers have open flames. Take care not catch hair, scarves, and/or sleeves on fire. Equipment can get very hot so there is a danger of serious burns. Boiling water can cause serious burns. Handle it carefully. II. INTRODUCTION The general gasgives the mathematical relationship between pressure, volume T, T and temperature of a gas as the conditions are changed from a first set of conditions to a second set of conditions. In this experiment you will measure the volume, temperature and pressure of a gas for two sets of conditions hot and cold. V2, the volume of the cold gas, can be calculated from the general gas law using the other five measurements and then compared with the measured v using percent difference: %diff- calculated)-V(measured) difference will indicate good agreement between experiment and the general gas lavw x100%. A small percent V, (measured) The general gas law applies only to situation in which the number of molecules of gas is unchanged from set of conditions 1 to set of conditions 2. This experiment starts with a dry gas when hot, but ends up with a gas in contact with water when cool. A gas in contact with water always takes in some water molecules. This additional gas can be accounted for by using Dalton's Law: the total pressure of a gas mixture equals the sum of all the partial pressures. Petal Pa+ Pa The partial pressure, Pa, is the pressure the component gas A would exhibit if it were all alone at the temperature and volume of the mixture. Thus for the cool gas in this experiment, the total pressure is the sum of the pressure of the dry gas and the pressure of the water vapor: Pesctal Pay+Powatar So the pressure of the dry gas at the cool temperature is Pary Postal-Pmae. The general gas law should apply for changes in temperature, volume and pressure of the dry gas. The pressure due to the water is called the vapor pressure of the water. It depends only upon the temperature of the water in equilibrium (contact) with the gas mixture and can be found in a table of water vapor pressures. (See page 6)

Explanation / Answer

from the given data:

hot gas-

V1=355ml (trial 1)

P1=748.03 torr

T1=373.45 K

V2=?

P2=729.491 torr

T2=294.05 K

V2=290 ml(measured)

V2(calculated)=P1V1 T2/T1P2=748.03 torr*355ml*294.05K/373.45K*729.491 torr=286.626 ml

2) percent diff between V2(mesured) and V2(calculated)=[difference in volume/V2(cal)]*100 =[290.05-286.626/286.626]*100=1.194%

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