Question

.44 The compressed air tank of a scuba diver reads 3,200 psi at the beginning of a dive and 825 psi at the end of a dive. Convert each of these values to atm and mmHg. 6.48 If someone takes a breath and the lungs expand from 4.5 L to 5.6 L in volume, and the initial pressure was 756 mmHg, what is the pressure inside the lungs (in mmHg) before any additional air is pulled in? 6.52 How hot must the air in a balloon be heated if initially it has a volume of 750. L at 20.oC and the final volume must be 1,000. L? 6.56 If a plastic container at 1.0oC and 750. mmHg is heated in a microwave oven to 80.oC, what is the pressure inside the container (in mmHg)? 6.58 Assuming a fixed amount of gas, complete the following table:   P1 V1 T1 P2 V2 T2  a. 0.55 atm 1.1 L 340 K ? 3.0 L 298 K  0.0oC b. 735 mmHg 1.2 L 298 K 1.1 atm ?  ̶ 120oC c. 7.5 atm 230 mL 15 atm 0.45 L ? 6.62 Calculate the volume of each substance at STP. a. 4.2 mol N2 b. 6.5 g He c. 22.0 g CH4 6.64 What volume does 1.50  1024 molecules of CO2 occupy at STP? 6.66 How many moles of gas are contained in a compressed air tank for scuba diving that has a volume of 7.0 L and a pressure of 210 atm at 25oC? 6.68 If a cylinder contains 10.0 g of CO2 in 10.0 L at 325 K, what is the pressure? 6.74 If the pressure due to the striped spheres in the molecular art is 480 mmHg, what is the pressure due to the spotted spheres? What is the total pressure of the system? 

Answer 1

The compressed air tank of a scuba diver reads 3,200 psi at the beginning of a dive and 825 psi at the end of a dive. Convert each of these values to atm and mmHg.

1. 14.7 psi= 1 atm 3200 psi to atm= 3200/14.7 atm =217.6871 atm and 825 psi to atm= 825/14.7 =56.12 atm
2. From P1V1= P2V2   ( temperature constant ) P2= P1V1/V2= 756*4.5/5.6=607.5mm Hg
3. From V1/T1= V2/T2, T2= V2T1/V1= 1000*(20+273.15)/750=390.8 K
4. From P1/T1= P2/T2 T1= 1deg.c= 1+273.15= 274.15K P1= 750 mm Hg T2= 80 deg.c= 80+273.15= 355.15K P2= P1*T2/P2= 750*355.15/274.15=971.594 mm Hg
5. A) From P1V1/T1= P2V2/ T2 , P2= P1V1T2/P2T1= 0.55*1.1*298/3*340=0.176 atm

B) 735*1.2/298=1.1*760*V2 /(120+273.15),V2= 735*1.2*393.15/(760*1.1*298)=1.39 L

C) not clear what to calculate

    6. 1 mole of any gas occupies 22.4 L, 4.2 moles of N2occupies =22.4*4.2=94.08L, Molecular weight of He = 4, moles of helium =6.5/4=1.625, Volume of 1.625 moles of gas at STP= 1.625*22.4 L=36.4L   C. 1 mole of any gas contains 6.023*1023 molecules and 1 mole of any gas occupies 22.4 L

7. 6.023*10²³ molecules occupy 22.4 L

10²⁴ molecules of CO2 ocupies 10²⁴*22.4/6.023*10²³ =37.19 L

8. 22gm of CH4= 22/16 moles of CH4=1.375 moles of methane

1 mole of CH4 occupy 22.4 Liters at STP

1.375 moles occupy 1.375*22.4=30.8 L

9. Assuming 1.5 to be moles, volume occupied by 1.5 moles at STP= 1.5*22.4=33.6L

10. from PV= nRT. n = PV/RT = 210*7/(0.08206*(25+273.15)=60.08 moles

11. moles of CO2 in the cylinder, n= 10/44=0.2272 V= 10L, T= 325K P= nRT/V= 0.2272*0.08206*325/10=0.605 atm