Chemistry - Unit 2

what is a chemical change?

what is a chemical change?

a process resulting in the formation of a new substance

What is the general formula of a synthesis reaction

A + B → AB

Why do equations need to be balanced?

To make sure there is the same number of atoms on both sides of the reaction

What is a binary compound synthesis reaction?

two elements combine to form an ionic or molecular compound

What does a non-metal oxide + water form?

An acid

ex. carbon dioxide + water

What does a metal oxide + water form?

base

ex. sodium oxide + water

What do two compounds in a synthesis create?

One larger compound

Write of the formation of acid precipitation with sulfur

1. S(s) + O2(g) → SO2(g)

2. 2SO2(g) + O2(g) → 2SO3(g)

3. SO3(g) + H2O(l) → H2SO4(aq)

what is a natural way to neutralize acid lakes

limestone powder (naturally occurring base)

what is a decomposition reaction?

A compound is broken down into 2 or more elements or simpler compounds

general format of decomposition

AB → A + B

what is electrolysis?

an electric current is sent through a solution to split a compound into simpler compounds

what is thermal decomposition?

the use of heat as a reactant to split apart a compound

how does decomposition of a binary compound work?

A catalyst (ie. heat or electrolysis) of helps break apart a binary compound into elements

binary compound → elements

what is a catalyst?

anything that speeds up a chemical reaction but is not used in the reaction

how does decomposition of a metal nitrate work?

metal nitrate → metal nitrite + oxygen

how does decomposition of a metal carbonate work?

metal carbonate → metal oxide + carbon dioxide

how does decomposition of a metal hydroxide work?

metal hydroxide → metal oxide + water (often requires heat)

how do airbags work?

a dramatic slowing of the vehicle triggers a sensor which generates an electric pulse and ignites pellets of sodium azide. Reacts to for solid sodium and nitrogen gas which inflates the airbag

NaN3(s) → 2Na(s) + 3N2(g)

what is combustion?

the reaction of a substance with oxygen which produces one or more oxides, heat and light (sometimes sound)

what are the possible products of incomplete combustion?

CO2(g), CO(g), C(s), H2O(g)

what is a hydrocarbon?

a compound made of only hydrogen and carbon atoms

what are the products of complete combustion of a hydrocarbon?

carbon dioxide and water vapour

what is one way to visually see complete vs incomplete combustion?

Soot (carbon) residue and orange flame indicate incomplete combustion (produce more light than heat)

Blue flame indicates complete combustion (produces more heat than light)

Why is carbon monoxide dangerous?

It is a colourless, doorless and toxic gas that is a similar shape and size to oxygen. This allows it to bind to hemoglobin in your blood, limiting the oxygen supply to cells around your body

To balance incomplete combustion you must either be given the products or the amount of oxygen available

What are the diatomic elements?

Hydrogen, Oxygen, Fluorine, Bromine, Iodine, Nitrogen, Chlorine

How does a thermite reaction weld steel railroad tracks?

Powdered aluminum and powdered iron race and produce a lot of heat which melts the iron and allows it to fill the empty space to connect the two rails

What type of raction is a thermite reaction?

Single displacement

What is a thermite reaction?

An exothermic (heat-releasing) single displacement combustion reaction between powdered iron oxide and powdered aluminum

Why are aluminum-magnesium alloys desirable for construction?

Lighter, stronger and more resistant to erosion than pure aluminum

What is leaching?

a process that is used to extract a metal another substance by dissolving the metal in an aqueous solution

what solution is to extract gold from ore?

Sodium cyanide undergoes a displacement reaction with zinc

How is sulphur dioxide exhaust captured and converted to sulphuric acid?

Scrubbers are made up of a chamber with many filters which capture

What is the general formula of a single displacement reaction?

A + BC → AC + B

Does single displacement work in reverse? Why or why not?

no because one metal or halogen has a stronger force of attraction and reaction than the other single element

How do we know if a halogen will replace another halogen?

Based on the order of the periodic table. Iodine is the least reactive and won’t replace anything, fluorine is the most reactive and will always replace other halogens

What are the products of metal displacing hydrogen from an acid?

Ionic compound + hydrogen gas

What are the products of a metal displacing hydrogen from water?

metal hydroxide (base) + hydrogen gas

What state are single displacement compound products except for thermite reactions?

aqueous

Double displacement general formula

AX + BY → AY + BX

what is a double displacement reaction?

the positive ions of 2 ionic compounds exchange places to form 2 new Ionic compounds

What do low solubility compounds form?

precipitate(s)

what state are both reactants in a dd?

Aqueous

what happens if both products in a dd are aqueous?

no reaction

What happens when an acid and carbonate undergo double displacement?

ionic compound + water + carbon dioxide

What happens when a base and ammonium undergo double displacement?

Ionic compound + water + ammonia (NH3)

when reactants in a double displacement create an ionic compound + water ?

acid + base