Chemistry. Friday, February 16 th Tuesday, February 20 th, 2018

Transcription

1 Chemistry Friday, February 16 th Tuesday, February 20 th, 2018

2 Do-Now: Test Day Do-Now 1. Write down today s FLT Copy and complete: 2. The formula for density is d =. 3. Zeros are only significant when. 4. Avogadro s number is. 5. From moles, I can convert to,, or (if I m at STP). 6. If I m converting between different molecules, I need to use a, which I can determine from the. Take out your planner, ToC, and a calculator

3 FLT I will be able to demonstrate my mastery of stoichiometry by completing Unit Test J Standard HS-PS1-7: Use mathematical representations to support the claim that atoms, and therefore mass, are conserved during a chemical reaction

4 Chemistry Wednesday, February 21 st Thursday, February 22 nd, 2018

5 Do-Now: On Worksheet 1. Complete the front page of the packet up front 2. When finished, take our your planner and ToC

6 BrainPOP: States of Matter Watch the BrainPOP video We will complete the packet questions after the video

7 FLT I will be able to describe three factors that affect gas pressure by completing Ch. 13 CN A Standard HS-PS1-5: Apply scientific principles and evidence to provide an explanation about the effects of changing the temperature or concentration of the reacting particles on the rate at which a reaction occurs.

8 Ch. 13 Notes A: Properties of Gases

9 Recall

10 Recall 3 states of matter: solid, liquid, and gas. All matter is made up of tiny particles

11 Recall Gas: Indefinite shape and volume (takes the shape and volume of its container) It s easily compressed because there s so much empty space. Gas particles move at high speeds and randomly.

12 Compressibility

13 Compressibility The molecules in gases are in constant motion This allows gases to expand until it fills its container

14 Compressibility The reverse is also true: Compressibility: Gases are easily compressed, or squeezed into a smaller volume, when pressure increases

15 Compressibility This is the idea behind placing air bags in automobiles In an accident, the air compresses more than the steering wheel or dash when you strike it The impact forces the gas particles closer together, because there is a lot of empty space between them

16 Review: Kinetic Energy

17 Kinetic Energy Kinetic energy: Energy an object has because of its motion Think about it: To accelerate an object, we must apply a force. But once applied, energy has been transferred to the moving object. Kinetic energy is simply the energy an object has because of its motion

18 Kinetic Energy All matter consists of tiny particles that are in constant motion. In a gas, these particles are molecules or atoms

19 Kinetic Energy & Gases In the 1800s, scientists were studying gases. How could they describe the properties of substances with no fixed shape or volume?

20 Kinetic Theory Applied to Gases 1. Gases are made of molecules. These are tiny spheres with insignificant volume 2. Molecules are in constant, random motion. They have kinetic energy. 3. Collisions are perfectly elastic. When molecules collide, they do not lose kinetic energy

21 Recall: Gas Pressure

22 Gas Pressure Pressure is defined as force per unit area For example, a high heel shoe exerts a greater pressure than a normal shoe due to the smaller area of contact Larger shoes spread out the force over a greater area

23 Gas Pressure Gas particles exert pressure when they collide with the walls of their container Individual gas molecules exert a minimal pressure Gas pressure: Caused by collisions of many particles against objects

24 Factors Affecting Gas Pressure

25 Factors Affecting Gas Pressure Four Variables for Describing Gases: 1. Pressure (P) usually in kpa 2. Volume (V) in L 3. Temperature (T) in K 4. Amount (n) in mol P, V, T, and n are variables kpa, L, K, and mol are units V, T, and n affect the Pressure of a gas

26 Factors Affecting Gas Pressure Number of Moles (Amount): When we inflate a balloon, we are adding gas molecules. Increasing the number of gas particles increases the number of collisions thus, the pressure increases If T is constant, then doubling the number of particles doubles the pressure

27 Factors Affecting Gas Pressure Amount (n): More molecules means more collisions, and Fewer molecules means fewer collisions. P and n are directly related én à ép ên à êp

28 Factors Affecting Gas Pressure Volume (V): In a smaller container, the molecules have less room to move. The particles hit the sides of the container more often. P and V are INVERSELY related êv à ép év à êp

29 Factors Affecting Gas Pressure Temperature (T): As temperature increases, molecules move faster As temperature decreases, molecules move slower P and T are directly related ét à ép êt à êp

30 Pair-Share-Respond 1. Describe the particles and motion of a gas 2. Identify the main ideas of the Kinetic Molecular Theory 3. What causes gas pressure? 4. Identify three factors that affect gas pressure 5. State if the three factors are DIRECTLY or INVERSELY related to pressure

31 CW Gas WS A ToC and/or study Ch. 13

32 Chemistry Friday, February 23 rd Monday, February 26 th, 2018

33 Do-Now: Ch. 13 CN Part B 1. Write down today s FLT 2. State one part of the Kinetic Molecular Theory applied to gases 3. What are the three factors that affect gas pressure? 4. If you increase the temperature of a gas, what happens to pressure? 5. If you increase the volume of a gas, what happens to pressure? Take out your planner, ToC, and a calculator

34 FLT I will be able to describe and quantify the relationships among temperature, pressure, and volume of a gas by completing Ch. 13 CN B Standard HS-PS1-5: Apply scientific principles and evidence to provide an explanation about the effects of changing the temperature or concentration of the reacting particles on the rate at which a reaction occurs.

35 Ch. 13 CN B: The Gas Laws

36 Recall

37 Factors Affecting Gas Pressure Four Variables for Describing Gases: 1. Pressure (P) in kpa 2. Volume (V) in L 3. Temperature (T) in K 4. Number of Moles (n) in mol V, T, and n affect the Pressure of a gas

38 Factors Affecting Gas Pressure Direct or Inverse Relationship? Pressure and Amount (P and n)

39 Factors Affecting Gas Pressure Direct or Inverse Relationship? Pressure and Volume (P and V)

40 Factors Affecting Gas Pressure Direct or Inverse Relationship? Pressure and Temperature (P and T)

41 Gas Laws

42 The Gas Laws The gas laws tell us how gases behave The amount of change can be calculated with mathematical equations.

43 Boyle s Law

44 Robert Boyle ( ) Boyle became interested in medicine and the new science of Galileo and studied chemistry. A founder and an influential fellow of the Royal Society of London Wrote extensively on science, philosophy, and theology.

45 Boyle s Law When T is held constant, P is inversely proportional to V

46 Boyle s Law Equation: P / V = k P 1 V 1 = P 2 V 2 (T must be constant)

47 Boyle s Law Ex 1/ A balloon contains 30.0 L of He gas at 103 kpa. What is the volume of He when the balloon rises to an altitude where the pressure is only 25.0 kpa? Assume that T remains constant.

48 Ex 2/ Nitrous oxide (N 2 O) is used as an anesthetic. The pressure on 2.50L of N 2 O changes from 105 kpa to 40.5 kpa. If the temperature does not change, what will the new volume be?

49 Charles s Law

50 Jacques Charles ( ) French Physicist Part of a scientific balloon flight on Dec. 1, 1783 was one of three passengers in the second balloon ascension that carried humans This is how his interest in gases started It was a hydrogen filled balloon good thing they were careful!

51 Charles s Law When P is held constant, T is directly proportional to V

52 Charles Law Gas law problems involving temperature will always require that the temperature be in Kelvin. Reason? There will never be a zero volume, since we have never reached absolute zero. Kelvin = C and C = Kelvin - 273

53 Charles s Law Ex 1/ A balloon inflated in a room at 24 C has a volume of 4.00 L. The balloon is then heated to a temperature of 58 C. What is the new volume if the pressure remains constant?

54 Charles s Law Ex 2/ If a sample of gas occupies 6.80 L at 325 C, what will its volume be at 25 C if the pressure does not change?

55 Gay-Lussac s Law

56 Joseph Louis Gay-Lussac ( ) French chemist and physicist Known for his studies on the physical properties of gases. In 1804 he made balloon ascensions to study magnetic forces and to observe the composition and temperature of the air at different altitudes.

57 Gay-Lussac s Law When V is held constant, P is directly proportional to T

58 Gay-Lussac s Law Ex/ A sample of nitrogen gas has a pressure of 6.58 kpa at 539 K. If the volume does not change, what will the pressure be at 211 K?

59 Combined Gas Law

60 Combined Gas Law When only n is constant, we can relate P, T, and V.

61 Combined Gas Law Ex/ 1 The volume of a gas-filled balloon is 30.0 L at 313 K and 153 kpa pressure. What would the volume be at standard temperature and pressure (STP)? (1atm = kpa)

62 Combined Gas Law Ex/ 2 A gas at 155 kpa and 25 C has an initial volume of 1.00 L. The pressure of the gas increases to 605 kpa as the temperature is raised to 125 C. What is the new volume?

63 CW Ch. 13 WS B ToC and/or study Ch. 13