Unit 1 Heat and Thermochemistry

Question 1

solid:
liquid:
gas:

Answer 1

particles are tight in a pattern with a definite volume and shape

particle are loosely packed, they move past one another; definite volume, takes shape of container

particles are apart and move around a lot; indefinite shape and takes shape of container and can be compressed

Question 2

Element:
compound:
mixture:

Answer 2

made of one atom

chemical substance made of 2 or more elements; are chemically combined so has different properties than elements

two or more elements that are not chemically combined

Question 3

physical property:
chemical property:

Answer 3

can be observed/measured without changing the identity of the substance; is reversible

how matter reacts when a chemical change happens

Question 4

Temperature:
when particles move apart ________ increases.

Answer 4

average kinetic energy of particles, potential energy increases

Question 5

Thermal energy:
if either _______ or _______ increases, the thermal energy increases.

Answer 5

the sum of all of the energy in a substance (total energy) ; including kinetic and potential, kinetic, potential

Question 6

_________ influences thermal energy. Objects can have the same temperature but different thermal energy due to ——–.

Answer 6

mass

Question 7

Heat:
This is in the unit of Joules

Answer 7

thermal energy that flows from high temperature to low temperature.

Question 8

heat flows from _______ to _________ until the temperatures are ________ or in _________.

Answer 8

high, low, equal, thermal equilibrium

Question 9

specific heat:
this varies depending on the ___________.

Answer 9

the amount of heat needed to raise temp of unit mass by 1 C, substance

Question 10

High specific heat:
Low specific heat:

Answer 10

take more energy to raise OR lower the temperature

takes less energy

Question 11

What is the formula for calculating temperature change?

Answer 11

q = mcdeltat

Question 12

If heat is released then q is ________ if absorbed then q is ________.

Answer 12

negative, positive

Question 13

For the same mass of a substance, molecules of _________ have more thermal energy and higher temp than _________. and has more than _________.

Answer 13

gas, liquid, solid

Question 14

What is the final temperature?
1. same mass and same specific heat
2. same mass and different specific heat
3. different mass and same specific heat

Answer 14

1. exactly halfway
2. closer to the initial temperature of the higher specific heat
3. closer to the substance with a higher mass

Question 15

A cooling curve is _______________. A heating curve is __________.

the ________ shows the phase that it is in. changes in _________ Use: _____

________ shows the phase change were there is NO ________. Use: _________

during a phase change the energy is working to change the phase.

Answer 15

negative and losing energy, positive and gaining energy, slopes, temperature, q=mct, straight line, temperature change, mhfusion/vaporization

Question 16

___________ is the study of thermal energy changes that occur in a nearly isolated system

Answer 16

calorimetry

Question 17

system is ___________
surroundings _________
boundary __________

Answer 17

the item being observed, anything outside the system, layer that separates system and surroundings.

Question 18

Types of systems:
closed ___________
open ________
isolated ___________

Answer 18

no mass transfer yes energy transfer
yes mass yes energy
no mass no energy

Question 19

When q is negative the _______ is giving heat to _________ and when q is positive it is the opposite.

Answer 19

system, surrounding

Question 20

What is the equation for calorimetry?

Answer 20

mct = -mct

Question 21

exothermic _____________
endothermic ______________

Answer 21

heat exiting, energy released in light or heat, feels warmer

heat is entering, absorbed, feels cold

Question 22

Activation energy ____________

Answer 22

energy required to break bonds for a chemical reaction to occur, the highest point of the graph

Question 23

if energy of reactants is greater than products - ___________-

if energy of reactants is less than products ______________.

Answer 23

exothermic, endothermic

Question 24

look at notes to see graphs.

Answer 24

look

Question 25

___________ as molecules heat up and move faster, they spread apart and objects expand.

Answer 25

thermal expansion

Question 26

Conduction
__________
__________
________ are good conductors since molecules are close to each other

Answer 26

heat transfer through direct touching
heat will move through the whole object; passed from molecule to molecule
solids

Question 27

convection
__________
fluids _____________
___________ circular movements of heated fluids that help spread heat

hot air rises since it is less dense and then cool air sinks since it is more dense

Answer 27

passes through fluids, anything that has loosely moving molecules = liquid and gas, convection currents

Question 28

radiation
___________
___________
___________

Answer 28

heat moves where there are no molecules
electromagnetic energy, travels in waves
can feel heat without touching

Question 29

when bonds are broken ____________. when bonds are put together energy is ______________

Answer 29

energy must be supplied, released

Question 30

_________ more energy is taken in to _________ of the reactants (activation energy) than ________ by the bonds being formed, therefore energy is absorbed.

Answer 30

endothermic, break the bonds, released

Question 31

_______________ more energy is ___________ when products are formed than energy used to ___________ (activation energy) of the reactants, therefore energy was released.

Answer 31

exothermic, released, break the bonds

Question 32

A + B -> C + energy - ________
A + B + energy -> C - ___________

Answer 32

exothermic

endothermic