Chm420 Lab Report

[pic 1]

CHM 420 LAB REPORT

NAME                        : FARAH NADIRA BT AZNOOR HISHAM

EXPERIMENT NO     : 8

TITLE                            : GAS LAWS        

GROUP PARTNER   : NOOR FAZLIN BT AHMAD

                          CHERLICE ALLESSANDRA BT SEMINDING

LAB INSTRUCTOR   : DR AMALINA MOHD TAJUDIN

TITLE

Gas Laws

OBJECTIVE

1. To verify the Graham’s law by measuring the distance travelled during the same period of time by two different gases of known molecular mass
2. To determine the molar mass of a volatile liquid by measuring mass of vapour of the liquid is needed to fill a flask of known volume at a particular temperature and pressure

CHEMICALS & APPARATUS

INTRODUCTION

There are four properties of gases which are pressure, volume, amount (moles) and temperature. Pressure is defined as the force the gas exerts on a given area of the container in which it is contained and unit for pressure is the Pascal, Pa. Volume is the three dimensional space inside the container holding the gas. The SI unit for volume is the cubic meter, m3. By definition, one mole of a substance contains approximately 6.022x1023 particles of a substance. Temperature defined as the measurement of hot and cold usually using thermometer. The SI units for temperature is Kelvin, K. Generally, there are three gas laws which are Boyle’s Law, Charles’s Law and Avogadro’s Law. Boyle’s Law describes the relationship between pressure and volume of gases. The pressure of a fixed amount of gas at a constant temperature is inversely proportional to the volume of the gas. For Charles’s Law, it describes the relationship between volume and temperature of gases. At a constant pressure, the volume occupied by a fixed amount of gas is directly proportional to its absolute temperature. Avogadro’s Law describes the relationship between volume and moles of the gases. At constant pressure and temperature, the volume of a gas is directly proportional to the number of moles of the gas present. Graham’s Law of Effusion is defined as the rate of effusion of a gas is inversely proportional to the square root of its molar mass.

PROCEDURE

1. Graham’s Law

1. A 50 cm length of glass tubing was obtained and dried. Two cotton swabs was prepared.
2. Using dropper pipettes, 20 to 25 drops of concentrated HCl was placed on the cotton swab and 20 to 25 drops of concentrated NH3 on another cotton swab
3. Using tweezers, the moistened end of the cotton swabs were inserted into opposite ends of the tube. The time needed for the appearance of the faint white cloud (ring) of ammonium chloride was noted
4. After several minutes, a white ring is formed. The point on the tube where the white ring is formed was marked. The distance travelled by each gas was measured. The data was recorded
5. The cotton swabs were removed using tweezers and immersed into a beaker of tap water
6. The tubing was rinsed with water and dried using acetone

1. Molar Mass of Volatile Liquid

1. A boiling water bath was set up using a 400mL beaker containing 250mL of water
2. Boiling chips was added into a conical flask. The mouth of conical flask was tightly covered with a small square of aluminium foil. A small hole was made on the foil cap
3. The empty, capped flask was weighed together with boiling chips
4. The foil cap was removed. A 2mL sample of the liquid was placed and the foil was replaced
5. The flask was clamped with a single burette clamp. The flask was transferred to the boiling water bath, immersed and heated.
6. The liquid refluxing inside the flask was noted. The flask was slightly titled.
7. The heating is continued until liquid is no longer visible and no vapour can be seen emerging from the pinhole. The heating was continued 30 seconds beyond this time
8. The flask was removed and placed on a tile. The clamp was removed and the flask was cooled it on the room temperature
9. The flask was dried and weighed the flask, cap and condensed vapour
10. The contents of the flask was disposed in waste bottle. The flask was filled with tap water and poured into a 500mL graduated cylinder. The volume was measured and recorded
11. The barometric pressure was measured and recorded. The data was recorded

RESULT & DISCUSSION

Observation of NH4Cl appearance: A white ring formed

Unknown liquid number or letter: Acetone, C3H6O