Chemical reactions Flashcards
What does the law of conservation of mass state?
The mass of products is always equal to the mass of reactants, mass is conserved. No atoms are destroyed or produced, they are simply rearranged. Chemical bonds and broken and new ones are formed, making new bonds.
What is the MASH?
metal + base = salt and “HOFBrINCl” (element in base) e.g. h2
Zinc + Hydrochloric Acid
Zn+2HCl→ZnCl2+H 2
What is BASH?
base + acid = salt + h20
Hydrochloric Acid + Sodium Hydroxide
HCl+NaOH→NaCl+H2O
What is “HOFBrINCl”?
used to name left over substance in mash - always 2 of them e.g. h2.
h2,
o2
f2
br2
I2
N2
Cl2
What are the 6 different chemical reactions?
Synthesis, decomposition, single-replacement, double-replacement, combustion and neutrilisation
What’s a synthesis chemical reaction?
Two or more substances combine to form one new substance OR COMPOUND
A + B = AB or AB + CD = ABCD
What’s a decomposition chemical reaction?
A substance breaks down into two or more simpler substances
AB = A + B
REVERSE OF SYNTHESIS
What’s a single replacement chemical reaction?
A more reactive element replaces a less active element (more reactive metal in a salt)
A + BC = AC + B
USE REACTIVITY SERIES (PRACTICE A BIT)
What’s a double replacement chemical reaction?
Two elements from two different compounds swap places Usually occur in aqueous solutions and produce a precipitate, a gas or water. A CATION CAN ONLY REPLACE ANOTHER CATION.
AGNO3 + NACL = AGCL + NANO3
(CHECK PPT AND SOLUBILITY DATA IN BOOK - PRACTICE A BIT)
What’s a neutralisation chemical reaction?
An acid and a base react together to form a salt and water.
e.g.: HCl + NaOH → NaCl + H2O
What are the 2 types of combustion reactions?
complete and incomeplete
What is a complete combustion chemical reaction - hydrocarbons?
Occurs when there is an excess of oxygen, meaning enough O₂ is available to fully react with the hydrocarbon.
Products: Carbon dioxide (CO₂) and water (H₂O).
Releases: A large amount of heat and light, making it highly efficient.
C3H8+5O2→3CO2+4H2O
(Propane + Oxygen → Carbon Dioxide + Water)
What is an incomplete combustion chemical reaction - hydrocarbons?
Occurs when oxygen supply is limited, meaning the hydrocarbon does not fully react with oxygen.
Products: Carbon dioxide (CO₂), carbon monoxide (CO), water (H₂O), and sometimes carbon (C, soot).
Energy Output: Less energy is released compared to complete combustion, making it less efficient.
2C3H8+9O2→4CO2+2CO+8H2O
(Propane + Limited Oxygen → Carbon Dioxide + Carbon Monoxide + Water)
What happens in a combustion of metals reaction?
Metals can burn in oxygen to form metal oxides.
Reaction Speed: Fast and highly exothermic (releases heat).
Example: Magnesium combustion is often demonstrated in labs because it burns with an intense white flame.
(Magnesium + Oxygen → Magnesium Oxide)
What happens in corrosion of metals?
A slow reaction between a metal and oxygen over time.
Results in metal oxides forming on the surface, weakening the metal.
Rusting: A specific type of corrosion that occurs in iron when exposed to oxygen and moisture (water).
(Iron + Oxygen → Iron Oxide (Rust))
