Reporting Category 4: Gases and Thermochemistry

8 STAAR Questions* Indicates readiness standards

*9A - Describe and calculate the relations between volume, pressure, number of moles, and temperature for an ideal gas as described by Boyle’s law, Charles’

law, Avogadro’s law, Dalton’s law of partial pressure, and the ideal gas law.

BOYLE’S LAW

As pressure increases, volume decreases.

Charles' Law

As volume increases, temperature increases.

Avogadro’s Law

Avagadro's Law

As volume increases, temperature increases

Dalton's Law of Partial Pressure

Volume must be in L, Temperature must be in K.1000 ml = 1 L

Kelvin = degrees celcius + 273

Ideal Gas Law

9C Kinetic Molecular theoryPostulates

1. A gas consists of a collection of small particles traveling in straight-line motion and obeying Newton's Laws.2. The molecules in a gas occupy no volume (that is, they are points).3. Collisions between molecules are perfectly elastic (that is, no energy is gained or lost during the collision).4. There are no attractive or repulsive forces between the molecules.5. the average kinetic energy or a molecule is 3 kT/2. (T is the absolute temperature and k is the Boltzmann constant)

11A understand energy and its forms, including kinetic,

potential, chemical, and thermal energies; kinetic energy - energy which an object possesses due to its motion

Potential energy - energy available by virtue of an object's position

Chemical energy - energy stored within the bonds of chemical substances

Thermal energy - energy associated with the random motion of atoms and molecules

11B understand the law of conservation of energy and the processes of heat transfer;

law of conservation of energy states that energy may neither be created nor destroyed

*11C use thermochemical equations to calculate energy changes that occur in chemical reactions and

classify reactions as exothermic or endothermicExothermic processAny process that gives off heat - transfers thermal energy from the system to its surroundings.

Endothermic processAny process in which heat has to be supplied to the system from the surroundings

Enthalpy - Used to quantify the heat flow into or out of a system in a process that occurs at constant pressure.

Heat content is accounted for by a change in "heat flow" of the reaction system.

Endothermic reaction: H>0 1.Enthalpy of the products >Enthalpy of reactants 2. Heat absorbed goes to increase the enthalpy of the reactions system

B. Exothermic reaction: H<0 1. enthalpy of products < enthalpy of reactants 2. Heat is evolved at the expense of the reaction system

11D perform calculations involving heat, mass, temperature change, and specific heat

Example: Gold has a specific heat of 0. How many joules of heat energy are required to raise the temperature of 15 grams of gold from 22 °C to 85 °C?

q = ?m = 15 gc = 0.129 J/g°CΔT = 85°C -22°C = 63°C

q = mcΔTq = (15 g)(0.129 J/g°C)(63 °C)q = 121.9 J 120 J

11E use calorimetry to calculate the heat of a chemical process