7. What is the molar mass of each of the following elements? a) helium, He(s)
c) potassium, K(s)
b) manganese, Mn(s)
d) boron, B(s)

The molar mass of:

Helium = 4.00 g/mol

Potassium = 39.0983 g/mol

Manganese = 54.94 g/mol.

Boron = 10.81 g / mol

Explanation:

Helium = 4.00 g/mol

Potassium = 39.0983 g/mol

Manganese = 54.94 g/mol.

Boron = 10.81 g / mol

Helium= 4.00g/mol

Potassium= 39.0983g/mol

Manganese= 54.94g/mol

Boron= 10.81g/mol

Explanation:

answer: the enthalpy of the overall chemical reaction is +87.88 kj or +88 kj.

according to hess's law, the overall enthalpy of a reaction is the difference between the sum of enthalpy values of all the products and the sum of enthalpy values of all the reactants.

δh(reaction) = ∑nδh(products) - ∑nδh(reactants)

δh(reaction) = [δh +δh] - [δh]

δh(reaction) = [1(-287.02) + 1(0) ] - [1(-374.9)] kj = +87.88 kj

here, δh (pcl3) = -287.02 kj, δh(cl2) = 0, δh(pcl5) = -374.9 kj

therefore, enthalpy of the overall reaction is +87.88 kj or +88 kj.

i just learnt this recently but i need to look through my notes again