Chapter 9 Pt 1 Flashcards by Lexie Schoenrock

_____ is anything that has the capacity to do work.
Think of it as something an object or a collection of objects can possess.
It can be exchanged between objects through contact.

Energy

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_______ is the flow of energy caused by a difference in temperature.

Heat

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______ is a force acting over a distance.

Formula?

Work

Energy = work = force x distance

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Think of _____ and ____ as the two different ways that an object can exchange energy with other objects.
Either out of it or into it

heat and work

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__________ is energy of motion or energy that is being transferred.

Kinetic energy

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____________ is the energy associated with temperature.
It is a form of kinetic energy.
Kinetic energy associated with molecular motion

Thermal energy

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____________ is energy that is stored in an object or energy associated with the composition and position of the object.
Energy stored in the structure of a compound

Potential energy

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Kinetic energy associated with the flow of electrical charge

Electrical

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Kinetic energy associated with energy transitions in an atom

Light or radiant energy

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Potential energy in the nucleus of atoms

Nuclear

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Potential energy due to the structure of the atoms, the attachment between atoms, the atoms’ positions relative to each other in the molecule, or the molecules’ relative positions in the structure

Chemical

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The amount of kinetic energy an object has is directly proportional to its mass and velocity
When the mass is in kg and velocity is in m/s, the unit for kinetic energy is a _____

joule (J)

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1 joule of energy is the amount of energy needed to move a __ mass at a speed of __

1 kg

1 m/s

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A ______ is the amount of energy needed to raise the temperature of one gram of water 1 °C.
1 __ = energy needed to raise 1000 g of water 1°C

calorie (cal)

kcal

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Conversion of calorie (cal) to joule (J)

1 cal = 4.184 J

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______ is the study of energy and its inter conversions.

thermodynamics

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The first law of thermodynamics is the _________

law of conservation of energy

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The first law of thermodynamics is the law of conservation of energy.
This means _______

This means that the total amount of energy in the universe is constant; it is conserved.
Therefore, you can never design a system that will continue to produce energy without some source of energy.

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part of the universe that is the focus of study

system

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everything in the study that is not part of the system

surroundings

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Universe =

System + Surroundings

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First Law of Thermodynamics: energy cannot be ________ only _______

energy cannot be created or destroyed, only changed in form (the total energy of the universe is constant)

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A system completely shut off from its surroundings so that neither matter nor energy can be transferred

isolated system

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If only energy can flow between system and surroundings

closed system

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If energy and matter can flow freely between system and surroundings

open system

sum of the kinetic and potential energy of all the particles that compose the system

Internal Energy (E or U)

internal energy =

kinetic energy + potential energy

change in energy when the collective internal energies of reactants are different than products formula?

Change in Internal Energy (ΔE aka ΔU) ΔEuniverse = ΔEsystem + ΔE surroundings = 0 ΔEsystem = -ΔEsurroundings

Internal energy is a state function | This means _________

The change in internal energy is independent of how it was acquired.

__________ are a “graphical” way of showing the direction of energy flow during a process.

Energy diagrams

If the reactants have a higher internal energy than the products, the change in energy will be _____ this process is ______

negative | exothermic

If the reactants have a lower internal energy than the products, the change in energy will be ______ this process is _____

positive | endothermic

If the reactants have a higher internal energy than the products: ΔEsys is said to be negative because energy flows ____` of the system into the surroundings.

out

If the reactants have a lower internal energy than the products: ΔEsys is said to be positive because energy flows ____ the system from the surroundings.

into

Therefore the internal energy of the system can be treated as: Energy flowing out of the system is like a withdrawal and therefore carries a ______ sign. Energy flowing into the system is like a deposit and carries a ______ sign.

negative | positive

``` Energy is exchanged between the system and surroundings through heat and work. __= heat (thermal) energy __= work energy heat and work are NOT state functions this means ____________ ```

q w their values depend on the process.

q (heat) when it is + - what happens to the system?

+ heat is going into the system so it gains thermal energy | - heat is leaving the system so it loses thermal energy

w (work) when it is + - what happens to the system?

+ work is done on the system (gaining work) | - work is done by the system (losing work)

ΔE (change in internal energy) when it is + - what happens to the system?

+ energy is flowing into the system (it is gaining energy) | - energy is flowing out of the system (it is losing energy

Which of these changes always results in an increase in the internal energy of the system?

The system absorbs heat and has work done on it by the surroundings.

Heat is the ______ of thermal energy between a system and surroundings.

exchange

Heat exchange occurs when system and surroundings have a difference in _______

temperature

is the measure of the thermal energy within a sample of matter.

temperature

Heat flows from matter with high temperature to matter with low temperature until both objects reach the same temperature. This is __________

thermal equilibrium

The increase in temperature is directly proportional to the amount of heat absorbed. The proportionality constant is called the

heat capacity, C. | Units of C (heat capacity) are J/°C or J/K.

The larger the heat capacity of the object being studied, the _____ the temperature rise will be for a given amount of heat.

smaller

The heat capacity of an object is proportional to the following:

Its mass | The specific heat of the material

The quantity of heat absorbed by an object can be determined if the following are known: Formula?

•Mass •Specific heat capacity •Temperature change q (heat in J) = m (mass in g) x Cp (specific heat) x ΔT (temperature change in Celsius or K)

The energy required to raise the temperature of an object by 1°C

``` Heat capacity (Cp) q = CpΔT Cp = J/Celsius ```

The energy required to raise the temperature of 1 gram of a substance by 1°C

Specific heat capacity (Cp) | Cp = J/ g x Celsius

The energy required to raise the temperature of one mole of substance by 1°C

Molar heat capacity (Cp,n) q = nCp,nΔT Cp,n = J/ mol x Celsius

When two objects at different temperatures are placed in contact, heat flows from the material at the _____ temperature to the material at the _____ temperature. Heat flows until both materials reach the ____ final temperature.

higher lower same

The amount of heat energy lost by the hot material _____ the amount of heat gained by the cold material.

equals

Thermal energy transfers heat from the metal to the water. The exact temperature change depends on the following: Formula?

The mass of the metal The mass of water Specific heat capacities of the metal and of water q metal = -q water

what is the heat capacity of water?

4.184 J/g x Celsius

Work is typically ________ work.

pressure-volume

PV work is work caused by a volume change against an external pressure. When gases expand, ΔV is ______, but the system is doing work on the surroundings, so wgas is ______. As long as the external pressure is kept constant, w= ____

positive negative –PΔV

ΔE = q + w, ΔEcan be determined by measuring q and w.In practice, it is easiest to do a process in such a way that there is no change in volume, so w= 0. At constant volume, _____

ΔEsys = qsys

In practice, temperature changes of individual chemicals involved in the reaction cannot be observed directly, so instead the temperature change in the surroundings is measured. Using an insulated container (i.e., controlled surroundings) The surrounding area is called a ________ and is usually made of a sealed, insulated container filled with water.

qsys = -qsurr bomb calorimeter qsurr= qcal = -qsys

To convert atm x L to joules

use 101.3 J = 1 atm x L

A bomb calorimeter s used to measure ΔE because it is a ___________

constant volume system

The heat capacity of the calorimeter is the amount of heat absorbed by the calorimeter for each degree rise in temperature and is called the ________

calorimeter constant | Ccal, kJ/Celsius

qcal = _____ | how do you find ΔErxn from this?

qcal = CcalΔT this gives you kJ qrxn = -qcal do -kJ divided by moles

The _______ of a system is the sum of the internal energy of the system and the product of pressure and volume. _ is a state function

enthalpy, H | H

H =

E + PV

The ______ of a reaction is the heat evolved in a reaction at constant pressure.

enthalpy change, ΔH

ΔH =

q (at constant pressure)

For an exothermic reaction, the temperature of the surroundings ____ due to a release of thermal energy by the reaction This extra thermal energy comes from the conversion of some of the chemical potential energy in the reactants into kinetic energy in the form of heat

rises

During the course of a reaction, existing bonds are broken and new bonds are made The products of the exothermic reaction have ____ chemical potential energy than the reactants. The difference in energy is released as heat

less

Exothermic energy flow (usually in the form of heat) from a system to its surroundings. Usually accompanied by an _____ in temperature of the surroundings. heat is written as a _____ The change in enthalpy is written as a _____ quantity

increase product negative

In an endothermic reaction, the temperature of the surroundings ____ due to absorption of some of its thermal energy by the reaction. During the course of a reaction, existing bonds are broken and new bonds are made The products of the reaction have ____ chemical potential energy than the reactants.To acquire this extra energy, some of the thermal energy of the surroundings is converted into chemical potential energy stored in the products.

drops | more

Endothermic: energy flow (usually in the form of heat) from surroundings into system. Usually accompanied by a _____ in temperature of the surroundings. In endothermic reactions, heat is written as a _______ The change in enthalpy is written as a ______ quantity

decrease reactant positive

The enthalpy change in a chemical reaction is an _____ property. The more reactants you use, the larger the enthalpy change. By convention, we calculate the enthalpy change for the number of moles of reactants in the reaction as written.

extensive

Reactions done in aqueous solution are at constant pressure. The calorimeter is often nested foam cups containing the solution. ΔHreaction= To get ΔHreaction per mol of a particular reactant, divide by the number of moles that reacted.

qconstantpressure= qreaction

Energy required to convert one mole of a solid substance at its melting point into the liquid state

Enthalpy of fusion (ΔHfus)

Energy required to convert one mole of a liquid substance at its boiling point into the vapor state

Enthalpy of vaporization (ΔHvap)

how do you find q of sold? (water) | what is ice's Cp?

q = mCp,iceΔT | 4.184 J/g x Celsius (same as water)

how do you find q of melting? | what is the ΔHfus for water?

q = nΔHfus | 6.01 kJ/mol

how do you find q of liquid? (water) | what is water's Cp?

q = mCp,waterΔT | 4.184 J/g x Celsius

how do you find q of vaporization? | what is the ΔHvap for water

q = nΔHvap | 40.65 kJ/mol

how do you find q of gas? (water) | what is steam's Cp?

q = mCp,steamΔT | 4.184 J/g x Celsius (same as water)

Chapter 9 Pt 1 Flashcards

(81 cards)