Chemistry Notes for Week 3
Chemistry Notes for Week 3 Chem 111
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This 3 page Class Notes was uploaded by Bailey Wilhoit on Sunday October 2, 2016. The Class Notes belongs to Chem 111 at University of South Carolina - Columbia taught by Stefik in Fall 2016. Since its upload, it has received 10 views. For similar materials see Chemsitry in Chemistry at University of South Carolina - Columbia.
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Date Created: 10/02/16
Chemistry Notes Week 3 Chapter 6 6.1 Vocabulary ● Pressure: force per unit area exerted on a surface Important to Know: ● Density of a solid is given in g/cm of g/mL ● Density of a liquid is given in g/mL ● Density of a gas is given in g/L ● One atmosphere (atm) is the normal (standard) pressure at sea level. The SI unit of pressure is the pascal (Pa) 2 ○ 1 Pa = 1 kg ∕m(s ) (chemists hardly use pascals) ○ 1 atm= 760 torr ○ 1 atm= 14.7 psi ○ 1 torr is equivalent to mmHg 6.2 Important to Know: ● Boyle’s Law: as pressure increases, volume decreases ○ P1 1 P2 2 ● Charles’s Law: as volume increases, temperature increases ○ P1T1= P2/T2 ● Gay Lussac’s Law: as pressure increases, temperature increases ○ P1T1= P2/T2 ● Avogadro’s Hypothesis: equal volumes of gases at the same pressure and temperature contain the same number of particles ○ Pressures in both containers are the same, but the masses of the gases are different ● Combined Gas Law: ○ P1 1T1= P2 2T2 ○ Example: A gas occupies 5.00 L at 0.974 atm. Calculate the volume of gas at 1.00 atm when the temperature is constant. 6.3 Important to Know: ● Ideal Gas Law ○ Pv=nRT ○ P= pressure (in atm) ○ v= volume ○ n= moles ○ R= 0.08206 (constant) ○ T= temperature (K) ● STP: T= 0°C, P= 1 atm ● Ex: ○ Calculate the molar mass of a gas if a 1.02 g sample at 220 mL at 95°C with a pressure of 750 torr. 6.4 Important to Know: ● The ideal gas law can be used to calculate the number of moles (n) in problems ○ It relates n to the volume of gas as molar mass is used with masses of solids and molarity is used with volumes of solutions ● Ex: ○ Calculate the volume of O g2 formed in the decomposition of 2.21 g of KClO 3 at STP 6.5 Vocabulary: ● Partial pressure: pressure exerted by each gas in a mixture ● Mole fraction (▯): number of moles of one component of a mixture divided by the total number of moles of substances present in the mixture Important to Know: ● For a mixture of two gases (A and B) the total Pressure is: ○ PT= PA PB ○ Ex: total pressure of a mixture of O and N is 4.51 atm. Experiment shows that O is present at 3.22 atm. Calculate the partial pressure of N ■ 4.51 3.22 = 1.29 ● Mole fraction: ○ ▯A + B +C = 1 ( for a mix of 3 gases) ○ The partial pressure of A in a mix is given by: PA= ▯A x PT ● Ex: Calculate partial pressure of Ar gas in a container with 2.3 mol of Ar and 1.1 mol of Ne with a total pressure of 1.4 atm.