When 1 mole of hydrogen gas (H2) reacts with excess oxygen to form water at a constant pressure, 241.8 KJ of energy is released as heat. Calculate ΔH for a process in which 21.9 g sample of hydrogen gas (H2) reacts with excess oxygen at constant pressure.

Explanation:

1. Gather all the information in one place

Mᵣ:   2.016  

          H₂ + ½O₂ ⟶ H₂O + 148.1 kJ

m/g:  21.9

2. Moles of H₂

3. Calculate ΔH

Treat the heat AS IF it were a reactant or product. In this case, the reaction is exothermic, so the heat is a product.

In effect, you have 148.1 mol of "kJ"s for each mole of hydrogen and

explanation:

let the different atoms be x and y. each with four protons and same mass will be represented as follows.

mass number is number of protons + number of neutrons.

            and  

since, it is given that one has a negative charge while the other is neutral. therefore, there will be increase in number of protons and the atom will be represented as follows.

according to periodic table, mass number of beryllium is 9 and it has atomic number 4 so, the atoms will be and .  

the protons and neutrons will be located inside the nucleus whereas the electrons will be revolving around the nucleus.