Sabreena, Olivia Jahari, Cindy Combined Law Sabreena, Olivia Jahari, Cindy

Definition/Description The combined law is a combination of Charles’ Law, Boyle’s Law and Gay- Lussac’s Law. It states the ratio between the product of the pressure and volume and the constant temperature of the system.

Equation P1V1 = P2V2 _________________ T1 T2 *if there’s two different conditions in the problem

Examples A car engine Shooting a gun Tires of a car-gas remains constant but the pressure increases. Spray cans-releases pressure causing the gas to expand in the bottle. Scuba diving- as the pressure increases the temperature decreases and the volume depends on the factors of the other two.

Pictures and graphs

Video https://www.youtube.com/watch?v=_wxhSanQyIs Stop at 4:14.

How to solve a problem that has different conditions Step 1: write out boyles law: p1v1=p2v2 Step 2: multiply by charles law:p1v1^2/t1=p2v2^2/t2 Step 3: multiply by gay lussacs:p162v1^2/t1^2=p2^2v2^2/t2^2 Step 4 : take square root to get combined law:p1v1/t1=p2v2/t2

Example problems A sample of sulfur dioxide occupies a volume of 652 mL at 40.° C and 720 mm Hg. What volume will the sulfur dioxide occupy at STP if the final pressure is at 760? A sample of nitrogen gas occupies a volume of 2.00 L at 756 mm Hg and 0.00° C. The volume increases by 4.00 L and the temperature decreases to 137 K. What is the final pressure exerted on the gas?

Answers to the Problems P1 = 720 mm P2 = 760 mm V1 = 652 mL V2 = ? T1 = 40.° C + 273 = 313 K T2 = 0° C + 273 = 273 K = 540 mL SO24

Answer to the Problems P1 = 756 mm P2 = ? V1 = 2.00 L V2 = 4.00 L T1 = 0.0° C + 273 = 273 K T2 = 137 K = 191. mm Hg