St. Valentine's Day has roots in several different legends. One of the earliest popular symbols of the day is Cupid, the Roman god of Love, who is represented by the image of a young boy with a bow and arrow.Three hundred years after the death of Jesus Christ, the Roman emperors still demanded that everyone believe in the Roman gods. Valentine, a Christian priest, had been thrown in prison for his teachings. On February 14,Valentine was beheaded. The night before he was executed, he wrote the jailer's daughter a farewell letter signing it, «From Your Valentine.Another legend tells us that this same Valentine, well-loved by all, wrote notes from his jail cell to children and friends who missed him.February 14 was also a Roman holiday, held in honour of a goddess. Young men randomly chose the name of a young girl to escort to the festivities.St. Valentine's Day is now a day for sweethearts. It is the day that you show your friend or loved one that you care. You can send candy to someone you think is special. Or you can send roses, the flower of love. Most people send «valentines, a greeting card named after the notes that St. Valentine wrote from jail. Valentines can be sentimental, romantic and heartfelt. They can be funny and friendly. If the sender is shy, valentines can be anonymous.Americans of all ages love to send and receive valentines. Handmade valentines are created by cutting hearts out of coloured paper. Valentines can be heart-shaped, or have hearts, the symbol of love, on them. In elementary schools, children make valentines for their classmates and put them in a large decorated box, similar to a mailbox. On February 14, the teachers open the box and distribute the valentines to each student. After the students read their valentines, they have a small party with refreshments.You can write a short rhyme inside the heart: Roses are red, Violets are blue, Sugar is sweet, And so are you!Or you can buy valentines with messages in them. If you are shy, you can sign it, «Your Secret Admirer».
Mg+2HCl = MgCl2+H2
MgCl2 + 2NaOH = Mg(OH)2 + 2NaCl
Mg(OH)2 = MgO+H2O
S + О2 = SO2
2SO2 + О2 = 2SO3
SO3 + Н2О = H2SO4
H2SO4 + 2КОН = K2SO4 + 2Н2О
С+О2 = СО2
СО2+СаО = СаСО3
СаСО3 + 2НNО3 = Са(NО3)2 + Н2О + СО2
CaCO3 + 2НСl = CaCl2 + H2O + CO2
K + O2 = KO2
KO2 + 3K = 2K2O
K2O + H2O = 2KOH
KOH + HNO3 = KNO3 + H2O
2KOH + H2SO4 = K2SO4 + 2H2O
4Na + O2 = 2Na2O
Na2O + H2O = 2NaOH
NaHSO4 + NaOH = Na2SO4 + H2O
4P+3O2= 2P2O3
3P2O3+4HNO3+7H2O = 4NO+ 6H3PO4
2 H3PO3 + 3 Mg(OH)2 = 6 H2O +Mg3(PO3)2
P2O5 + 6NaOH = 2Na3PO4 + 3H2O
2Fe+O2 = 2FeO
FeO+2HCl = FeCl2+H2O
FeCl2+2KOH = Fe(OH)2+2KCl
Fe(OH)2 =FeO+H2O
4P+5O2 = 2P2O5
P2O5 + 3H2O = 2H3PO4
H3PO4 + 3KOH = K3PO4 + 3H2O
K3PO4 + 3AgNO3 = 3KNO3 + Ag3PO4