1 mole of water = 18 grams (you can find this by finding mass of two hydrogen and one oxygen which is (1*2) + 16 = 18)
1.8 grams = 0.1 moles
1 H2O molecule has 10 electrons so 0.1 moles can be computed as:
(6.023*10^23)*(0.1)*10 = 6.023*10^23 electrons
Phosphorus 31. because the mass of sulfur 32 minus the number of protons 16 = 16 neutrons and the mass of phosphorus 31 minus the number of protons 15 = 16 neutrons
Final answer: phosphorus 31
Perspex and polythene are good examples of insulators.
The combustion of naphthalene is given as:
C10H8 (s) + 12 O2 (g) --> 10CO2 (g) + 4 H2O (l)
Enthalpy of combustion ΔH = -5157 kJ/mol
Now, the enthalpy change of a reaction is given
ΔH = ∑nΔHf (products) - ∑nΔHf (reactants)
where n = number of moles
ΔHf = enthalpy of formation
Therefore,
ΔH = [10*ΔHf(CO2) + 4*ΔHf(H2O)] - [1*ΔHf(C10H8) + 12*O2]
-5157 = [10*(-393.5) + 4*(285.83)] - [ΔHf(C10H8) + 12*(0)]
ΔHf(C10H8) = 78.68 kJ/mol
