January 2019 NY Regents Chemistry Exam

40 A rigid cylinder with a movable piston contains a sample of hydrogen gas. At 330. K, this sample has a pressure of 150.kPa and a volume of 3.50L. What is the volume of this sample at STP? (1) 0.233 L

(2) 1.96 L

(3) 4.29 L

(4) 6.26 L

Solution: Table T on the Reference Table has an equation for the Combined Gas Law.

It is P1V1/T1= P2V2/T2

Also, STP stands for standard temperature and pressure which can be found in Table A. Standard pressure is 101.3 kPa and standard temperature is 273 K. Let's now write out all the given.

P1=150.kPa P2=101.3 kPa

V1=3.50L. V2=?

T1= 330. K T2=273 K

All there is left to do is plug these numbers into the formula and solve for V2.

Answer: 3

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