Answer is: 0 (zero).
ΔHf is the standard enthalpy or heat of formation of the compound. Standard enthalpy is the change of enthalpy during the formation of one mole of the substance from elements. All elements in their standard states <span>have a standard enthalpy of formation of zero,so there is no change involved in their formation.</span>
Answer:
3.98g
Explanation:
Given parameters:
Number of molecules = 1.2 x 10²⁴ molecules
Unknown:
Mass of H₂ = ?
Solution:
To find the mass of this molecule, we use the expression below:
Mass = number of moles x molar mass
Molar mass of H₂ = 2(1) = 2g/mol
6.02 x 10²³ molecules are contained in 1 mole of a substance
So; 1.2 x 10²⁴ molecules will have = 1.99 moles of H₂
Mass of H₂ = 1.99 x 2 = 3.98g
It should be monitored because the o-zone layer holds all the gasses on earth and if it continues to grow, it can have devastating effects.
A,D,and E I hope this helps