Law of Conservation and mass

by David Barnes, Jarryd Karr, and Aaron Robledo.

Explanation of the Law of Conservation of mass/matter

The law of conservation of mass states that mass in an isolated system is neither created nor destroyed by chemical reactions or physical transformations. According to the law of conservation of mass, the mass of the products in a chemical reaction must equal the mass of the reactants.

Explanation of a reactant

a substance that participates in a chemical reaction, a substance that is present at the start of the reaction


  • Example- H2 and O2 are reactants in the reaction H2(g) + 1/2 O2(g) → H2O(l).

Explanation of a product

A product is a substance that is formed as the result of a chemical reaction



  • Example- AgCl (s) is the product of the reaction Ag+(aq) + Cl- (aq) → AgCl

Explanation of synthesis reaction

A synthesis reaction or direct combination reaction is a type of chemical reaction in which two or more simple substances combine to form a more complex product. The reactants may be elements or compounds. The product is always a compound.



  • Example- Synthesis of Water 2 H2(g) + O2(g) → 2 H2O(g)

Single Replacement

A single displacement reaction is a chemical reaction where one reactant is exchanged for one ion of a second reactant. Single displacement reactions take the form A + BC → B + AC


  • Example- Cu(s) + 2AgNO3(Aq) --> Cu(NO3)2(Aq) + 2Ag(s)

Double Replacement Reactions

A double replacement reaction is a chemical reaction where two reactant ionic compounds exchange ions to form two new product compounds with the same ions.Double replacement reactions take the form: A+B- + C+D- → A+D- + C+B-



  • Example- AgNO3 + NaCl → AgCl + NaNO3

Decomposition Reactions

A decomposition reaction is a type of chemical reaction where one reactant yields two or more products. AB→A+B



  • Example- 2 H2O → 2 H2 + O2

Acid Base Reactions

When an acid and a base are together they react to neutralize the acid and base properties, producing a salt. The H(+) cation of the acid combines with the OH(-) anion of the base to form water.



  • Example- NH3(g)+H2O(l)→NH+4(aq)+OH−(aq)

Combustion Reactions

A combustion reaction is a type of chemical reaction where a compound and an oxidant is reacted to produce heat and a new product.


  • Example- CH4(g) + 2 O2(g) → CO2(g) + 2 H2O(g)