HOLIDAY HMWRK DEFINITIONS

Question 1

Combustion reaction

Answer 1

a reaction in which a substance reacts with oxygen gas, releasing energy

Question 2

Exothermic

Answer 2

reactions that release energy to the environment

Question 3

Endothermic

Answer 3

reactions that absorb energy

Question 4

Chemical energy

Answer 4

the energy of chemical substances that is released when the substances undergo a chemical reaction and transform into other substances eg. heat content and enthalpy

Question 5

Heat content

Answer 5

The amount of heat energy available to be released by the transformation or use of a specified physical unit of an energy form. given by H base r

Question 6

Enthalpy or enthalpy change

Answer 6

measure of the quantity of energy absorbed or released during chemical reactions

Question 7

Activation energy

Answer 7

The energy required to break the bonds of reactants so that a reaction can proceed. Energy barrier that must be overcome before a reaction can commence.

Question 8

Energy profile diagram

Answer 8

a diagram that displays energy changes that occur during a period of chemical reaction

Question 9

Thermochemical equation

Answer 9

when the value (triangle)H is added to a balanced equation

Question 10

Sustainable

Answer 10

a scientific concept that seeks to improve the efficiency with which natural resources are used to meet human needs for chemical products and services

Question 11

Fossil fuels

Answer 11

naturally occurring fuels such as coal, oil or gas, that were formed in the geological past from the remains of living organisms

Question 12

Renewable fuels

Answer 12

fuels that can be replaced at a sustainable rate for large-scale energy production.

Question 13

Non-renewable fuels

Answer 13

resources that are used faster than they can be replaced eg. coal, oil and natural gas

Question 14

Photosynthesis

Answer 14

the endothermic chemical reaction carried out in chloroplasts in the cells of green leaves.

Question 15

Natural gas

Answer 15

fossil fuel that is found in deposits in the Earth’s crust and composed of methane and small amounts of other hydrocarbons, like ethane, and propane.

Question 16

Petrodiesel

Answer 16

a fraction of crude oil

Question 17

Biofuel

Answer 17

fuels derived from plant materials, such as grains, sugar cane, vegetable waste, and vegetable oils.

Question 18

Biogas

Answer 18

gas that is released in the breakdown of organic waste by anaerobic bacteria. the bacteria decompose the complex molecules contained in substances such as carbohydrates and proteins into simple molecular compounds, carbon dioxide and methane

Question 19

Biodiesel

Answer 19

a mixture of organic compounds called esters. These esters are produced by a chemical reaction between vegetable oils or animal fats and an alcohol (methanol)

Question 20

Bioethanol

Answer 20

produced from glucose and other sugars in a fermentation process. used for farming industries and forestry industries.

Question 21

Complete combustion

Answer 21

occurs when oxygen is plentiful. the only products are carbon dioxide and water.

Question 22

Enthalpy of combustion

Answer 22

the heat energy given out when one mole of a substance burns completely in oxygen. negative value that indicates that the equation is exothermic.

Question 23

Heat of combustion

Answer 23

the heat energy released when a specified amount (eg 1g, 1L, 1 mol) of a substance burns completely in oxygen and is, therefore, a positive value

Question 24

Molar enthalpy

Answer 24

enthalpy of a substance given per mole and is essentially the same as enthalpy of combustion for a fuel.

Question 25

Specific heat capacity

Answer 25

the measure of the amount of energy needed to increase the temperature of a specific quantity of that substance (usually 1 gram) by 1 degree. reflects types of bonds holding the molecules, ions or atoms together in the substance.