Chapter 5 Matter and Energy(1)

Chapter 5 Matter and Energy(1) - ore Concepts in Chemistry...

Info iconThis preview shows pages 1–13. Sign up to view the full content.

View Full Document Right Arrow Icon
Core Concepts in Chemistry Structure Properties Reactions Energy
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Chapter 5 Matter/Energy Energy (high density): the capacity of a system to do work (W=F.d). Types of Energy: Kinetic (KE) and Potential(PE). Total E (or U) = KE + PE Kinetic : matter in movement has kinetic energy (½ mV 2 ). Thermal, mechanical, electric. Potential: Energy stored as consequence of the position of matter (mgh, ½ kx 2 , etc.) Both types can be interconverted.
Background image of page 2
Kinetic Nature of Matter Kinetic Nature of Matter Matter consists of atoms and molecules in motion. Matter consists of atoms and molecules in motion.
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Positive and negative particles (ions) attract one another. Two atoms can bond As the particles approach they have a lower potential energy Potential Energy Potential Energy on the Atomic Scale on the Atomic Scale
Background image of page 4
Conservation of Mass/Energy Mass and energy are two expression of the same physical entity, they are never destroyed or created. Thermodynamics: the study of thermal energy transfer. First law of thermodynamics: The total energy of the universe is constant. Temperature (T): The average kinetic energy of the molecules of a system. (Energy density, intensive) Heat (q): the total amount of kinetic energy of all the molecules of a system (extensive property).
Background image of page 5

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Heat and Temperature Heat is measured by using an old standard unit of energy: the calorie. A calorie is the amount of heat needed to raise the temperature of 1g of liquid water by one (1 0 C) degree Celsius. Temperature is measured in degrees Celsius or in Kelvin. The former is related to the freezing and boiling point of water; the latter is an absolute measure of energy of molecules.
Background image of page 6
Heat Energy Equivalent James Prescott Joule was the first to demonstrate that MECHANICAL work is equivalent to HEAT energy. He used an apparatus that dropped a 1 Kg weight a certain distance, which spun a set of paddles inside water. He discover that, when 4.185 Joules dissipated in 1g of the water, an increased of the temperature of water by 1 degree Celsius (a calorie) occurred. Or 1 calorie = 4.185 Joules of energy
Background image of page 7

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Joule’s apparatus James Joule James Joule 1818-1889 1818-1889
Background image of page 8
Sparkler
Background image of page 9

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Temperature Temperature (T): The average kinetic energy of the molecules of a system. (Energy density, intensive) A burning match has a temperature of about 700 0 C. A sparkle from a fireworks sparkler is about 1300 0 C. The former can burn our fingers, but the latter can not. And neither one can boil a pound of water, or increase its temperature noticeable. Why?
Background image of page 10
A pound of water at 20 0 C has molecules that move slower, but their total amount of energy is more than that in the molecules of a match or a sparkle
Background image of page 11

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Internal Energy (E) The higher the T, The higher the T, the higher the the higher the internal energy internal energy So, use changes in T So, use changes in T (delta T, ∆T) to (delta T, ∆T) to monitor changes in monitor changes in E (∆E). E (∆E).
Background image of page 12
Image of page 13
This is the end of the preview. Sign up to access the rest of the document.

Page1 / 57

Chapter 5 Matter and Energy(1) - ore Concepts in Chemistry...

This preview shows document pages 1 - 13. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online