The number 2 IN FRONT is called a coefficient, and it tells you that there are two water molecules.
The number BETWEEN the "H" and the "O" tells you that in one single molecule of water, it is made of 2 atoms of hydrogen, and 1 atom of oxygen.
For example, if hydrogen gas (H2) is combined oxygen (O2), water (H2O) is formed. Because the formula is H2, two little "2" tells us that hydrogen gas is composed of 2 atoms of hydrogen. Same with oxygen -- O2 is made of two atoms of oxygen. The balanced equation for the reaction to form water is: 2H2 + O2 ---> 2H2O
What the numbers in front of the molecules mean is that 2 molecules of hydrogen combine with one molecule of oxygen to form 2 molecules of water.
See the Related Questions about balanced equations and stoichiometry for more about how coefficients are used and what they tell us about a reaction.
2 represents number of moles. It means there are 2 moles of water molecule.
4KO2(S) + 2H2O(l) ----> 4KOH(aq) + 3O2(g)There you are.
2K + 2H2O --> 2KOH + H2 The balanced equation shows that there is a 2 in front of water.
2
2 oxygen,4 hydrogen, 4 hydrogen, and 2 oxygen so overall 12
Hydrogen peroxide ... but its written as H2O2.
4KO2(S) + 2H2O(l) ----> 4KOH(aq) + 3O2(g)There you are.
Trihydrate - basically 3 molecules of water (just as dihydrate is 2H2O) Unless you're referring to the molecule 3H2O used in measuring the total body water - in that case it's 'tritiated water'
2K + 2H2O --> 2KOH + H2 The balanced equation shows that there is a 2 in front of water.
2H2O If H2O is a single water molecule, then placing the "2" in-front of it indicates that there are two whole molecules of water.
CaSO4 2H2O
2
Plaster of Paris is a type of building material based on calcium sulphate hemihaydrate CaSO4·1/2H2O. It is created by heating gypsum to about 150 °C. 2 CaSO4·2H2O → (2 CaSO4·H2O) + 3 H2O (released as steam).
Hydrogen peroxide ... but its written as H2O2.
Two molecules of water.
2 oxygen,4 hydrogen, 4 hydrogen, and 2 oxygen so overall 12
sodium nitrite
SrSO4 + 2H2O + 2NH3