1. Calculate the volume of 1.25 mol of nitrogen at 47 o C and 3.68 atm of pressu
ID: 832765 • Letter: 1
Question
1. Calculate the volume of 1.25 mol of nitrogen at 47 oC and 3.68 atm of pressure.
2. To make an isotonic solution for an IV, the molarity of NaCl in the IV must be the same as the molarity of blood. What is the molarity of NaCl in blood if 0.684 moles are present in 4.80 L of blood?
3. What is the concentration of arsenic, in parts per million, when 5.3 mg of arsenic are present in 80.0 g of soil?
4. A weather balloon is filled to 85.4 L when the atmospheric pressure is 736 mm Hg and the air temperature is 19 oC. It rises to where the atmospheric pressure is 533 mm Hg and the temperature is -23 oC. What is the new volume?
Explanation / Answer
(1) Ideal gas equation: PV = nRT
Volume V = nRT/P
= 1.25 x 0.08206 x (273.15 + 47)/3.68
= 8.92 L
(2) Molarity = moles of NaCl/volume of blood
= 0.684/4.80
= 0.1425 M = 0.143 M
(3) Mass of arsenic = 5.3 mg = 0.0053 g
Mass of soil = 80.0 g
Concentration = mass of arsenic/mass of soil x 10^6
= 0.0053/80.0 x 10^6
= 66.25 ppm = 66.3 ppm
(4) P1 = 736 mmHg, P2 = 533 mmHg
V1 = 85.4 L, V2 = ?
T1 = 19 deg C = 292.15 K, T2 = -23 deg C = 250.15 K
P1V1/T1 = P2V2/T2
736 x 85.4/292.15 = 533 x V2/250.15
Volume V2 = 101 L
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