5. Types of chemical reactions

Chemical reactions are processes by which atoms or molecules are redistributed, resulting in different substances with unique properties. Chemical reactions are classified into different categories according to the mechanics of the reactions. The original elements or compounds involved in a chemical reaction are called reactants, and the chemicals that result are called products. Classification of types is presented in Table 2.

Table 2. Types of chemical reactions

Type	Scheme	Example
Synthesis (combination, construction, composition) reactions	X + Y = Z, where X, Y are elements or compounds; Z - new compound	2 H2 + O2 = 2H2O; H2O + SO3 = H2SO4; K2O + CO2 = K2CO3
Decomposition (desythesis, decomposition, deconstruction) reactions	XZ = X + Z	2 KClO3 3 O2↑ + 2 KCl ; 6NaHCO3 3 Na2CO3 + 3 CO2↑ + 3H2O; 2 AgI 2 Ag + I2
Single replacement (single displacement, single substitution, activity replacement) reactions	A + BX = B + AX	2 Mg + TiCl4 Ti + 2 MgCl2; 2 Al + 6 CaO Ca3(AlO3)2 + 3 Ca;
Double replacement (double displacement or metathesis) reactions	AB + CD = AD + CB	AgNO3 + KCl = AgCl↓ + KNO3; TiCl4 + H2O = 4 HCl↑ + TiO2↓; HCl + NaOH = NaCl + H2O
Oxidation-reduction reactions (Red-Ox)	Az + n → A (z - n) By - m → B (y+m)	2Na + S → Na2S; 2 KMnO4 K2MnO4 + MnO2 + O2
Acid-Base reactions (neutralization)	H+ + OH- → H2O (in net ionic form)	H2SO4 + 2 NaOH = Na2SO4 + 2H2O

PRACTICE PROBLEMS

1. To determine relative molecular mass and molar mass of Potassium Orthophosphate К₃РО₄.

2. How many atoms and moles of atoms are contained in 64 g of Oxygen ¹⁶О? To calculate a mass of one atom of Oxygen in grams.

3. How many moles of H₂SO₄ are contained in 4,9 grams of this substance?

4. How many moles of Sulfuric acid is it possible to prepare from 6,4 kg of Sulfur?

5. How many moles of slack lime Са(ОН)₂ is it possible to prepare from 0,1 g of chalk СаСО₃ if chalk completely changed into slack lime?

6. To calculate mass (in g) of molecules of Chlorine Cl₂, Carbonic gas CO₂, ammonia gas NH₃.

7. How many grams of Barium Sulfate BaSO₄ may be prepared from 6,1 g of salt BaCl₂2H₂O? To calculate the mass of Sulfuric acid used in this reaction.

8. Solution, contained 12,6 g of Nitric acid HNO₃, was mixed with 7,2 g of Caustic soda NaOH. What substance will be rest in surplus and in which quantity?