the volume of air is 0.300 mL at 2.0 °C, when the barometric pressure in the roo

Question

the volume of air is 0.300 mL at 2.0 °C, when the barometric pressure in the room is 745.0 torr, then how many moles of air are in the U-tube? R = 6.237 x 104 mL . torr .
mol-1. K-1??

a. 7.43 x 10-8 moles

b. 6.75 x 10-3 moles

c. 4.50 x 10-1 moles

d. 1.30 x 10-5 moles

From your data in Part 1 of the experiment, you calculate the natural log of the partial pressure of water and 1/T value in K for 5 points between 50°C and 80°C. You make a graph of ln(P) vs. 1/T and determine that the slope of the linear line is       -4800 K. Use this information to calculate Hvap of water. Make sure to use R = 8.314 J .

39.9 kJ/mol

46.6 kJ/mol

31.5 kJ/mol

0.578 kJ/mol

39.9 kJ/mol

46.6 kJ/mol

31.5 kJ/mol

0.578 kJ/mol

Explanation / Answer

1) answer : d. 1.30 x 10-5 moles

explanation :

P = 745 / 760 = 0.980 atm

T = 2+ 273 = 275 K

V = 0.3 ml = 0.3 x 10^-3 L

R = 0.0821 L-atm /mol K

P V = n R T

0.980 x 0.3 x 10^-3 = n x 0.0821 x 275

n = 1.30 x 10^-5

2) answer : a ) 39.9 kJ

slope = - H / R

-4800 = - H / R

H = 4800 x R = 4800 x 8.314 x 10^-3

H = 39.90 kJ

(here R = 8.314 x 10^-3 kJ / mol K)

Related Questions

Navigate

• Browse (All)
• Browse T
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.