Agnes Tamatekou Professor Leveritt Chem 101 17 September 2021 Gases Lab Station I 1. When you inhale and suck the air out of the cup, the cup shrivels up. When you release some air, the cup loosens from your lips. 2. The number of moles in the cup is decreasing but increasing in your mouth. I assume the temperature remained constant. The outside pressure is increasing because the equilibrium is trying to balance out the pressure inside and outside the cup. The volume of the cup is decreasing too. Station II 3. When squeezing the empty plastic bottle with the top on it, the bottle got tighter and harder, but no air seemed to be coming out of it. When squeezing an empty plastic bottle without a cap, air is released from the top of the bottle. The bottle gets skinnier where you squeeze it. 4. When the cap is on the bottle, the number of moles and the temperature remain constant. The moles remain constant because the air can’t really escape the bottle since the cap is on. As you squeeze the bottle, the volume decreases. This, along with the fact that the number of moles remained constant in the bottle caused the pressure to increase because the air particles are hitting the walls of the bottle more frequently. You can see that the pressure was increasing because the bottle was swelling. When the cap is off and you squeeze the bottle, the air particles can escape through the top. This means that there are less moles of oxygen/are in the bottle and the volume decreases (a lot more than when the cap was on). All of this means the pressure also decreases because there are less particle hitting the walls of the bottle. Station III 5. When your hands touch the bottom of the hand boiler. the liquid ethanol pushes to the top and starts to boil. When your hand touches the top of the hand boiler, the liquid ethanol pushes to the bottom and starts to boil. When you hold the hand boiler in the middle the liquid ethanol stays there. 6. The number of moles remain the same, but it evaporates when the liquid ethanol pushes up or down. The liquid ethanol seems to boil at a low temperature. The small increase in temperature causes liquid to evaporate, therefore causing the pressure in the hand boiler to increase which is what makes the liquid go up or down when you touch it. Additional Questions 1. When discussing gases the term pressure means that the molecules are hitting the walls of a container. The more they hit these walls the higher the pressure. 2. 3. 4. 5. 6. 7. a. An example is the gas inside a balloon. The balloon inflates because the pressure is increasing because the number of moles of air in the balloon is increasing and this causes the particles to hit the walls of the balloon more often. b. A balloon would be a good example again because a gas fills up the balloon as much as it can until it pops. c. Boyles law: (pressure 1)(volume 1)=(pressure 2)(volume 2) d. Charles law: (volume 1)/(temperature 1)=(volume 2)/(temperature 2) When you convert helium to kelvin you get 50 + 273 = 323 and 25 +273 = 298. It is incorrect to say that 50 degrees of Celsius is twice as hot as helium at 25 degrees Celsius. Boyles law states that volume and pressure have an indirect relationship to each other. Here, in this example, A barometer balances the weight of the atmosphere against the weight of the mercury column. The atmospheric pressure balances the weight of the mercury and the air pressure. When mercury weights less then the air pressure then the pressure is higher, and vice versa. PV=nRT Mass= n(29) Na=6.022*10^23 (T= 25°C 298 K; Pressure= 1 atm ; Volume= 100 m^3 ; PV=nRT) N=1157 Mass= 2*29/Na =115*299/6.022*10^23 =40*10^-23 kg The temperature increases when we heat the gas, which leads to the pressure increasing. The kinetic energy of the particles mass is constant. Temperature is related to the kinetic energy, so the higher the temperature the higher the pressure because the particles are moving quicker. This means the piston is moving. The volume is also changing as the velocity increases.
