CHM 130 Spring 2007 Diebolt Take Home Quiz 5. Key
1) A 25.8 L sample of gas has a
pressure of 695 torr at 17 °C. What is
the volume if the pressure is changed to 1.85 atm and temperature to 72 °C? (5
pts)
T1 = 17 + 273 = 290 K V1 = 25.8 L
T2 = 72 + 273 = 345 K P2 = 1.85 atm V2
= ?
Solve for V2:
= 15.2 L
2) A sample of gas occupies 1.13 L at
STP. What is the pressure (atm) of this
gas if it occupies 725 mL at 65 °C? (5
pts)
V1 = 1.13 L STP:
T1 = 273 K P1 = 1 atm
T2 =
65 + 273 = 338 K P2 = ?
Solve for P2:
= 1.93 L
3) Calculate the mass percent
concentration of a MgCl2 solution prepared
by dissolving 25.0 g of MgCl2 in 525 g of water. (5 pts)
= 4.55 %
4) What
mass of water is required to dissolve 12.5 g of NaCl during the preparation of
a 7.25% NaCl solution? (5
pts)
= 160. g
water
5) Calculate the molarity of a K2SO4
solution prepared by dissolving 65.5 g of K2SO4 in 575 mL
of solution. (5 pts)
= 0.654
M K2SO4