PRACTICE
1 Chlorine has two stable isotopes, chlorine-35 and chlorine-37. The
atomic number of chlorine is 17. Calculate the numbers of protons,
electrons, and neutrons each isotope has.

1. For isotope A (chlorine 35)

Proton = 17

Electron = 17

Neutron = 18

2. For isotope B (chlorine 37)

Proton = 17

Electron = 17

Neutron = 20

Explanation:

Let isotope A be chlorine-35

Let isotope B be chlorine-37

1. For isotope A (chlorine-35)

Data obtained from the question include:

Atomic number = 17

Mass number = 35

Proton number = atomi number

Proton number = 17

Since the isotope is neutral,

Electron number = proton number

Electron number = 17

Mass number = Neutron + proton

Neutron = Mass number - proton

Neutron = 35 - 17

Neutron number = 18

2. For isotope B (chlorine-37)

Data obtained from the question include:

Atomic number = 17

Mass number = 37

Proton number = atomi number

Proton number = 17

Since the isotope is neutral,

Electron number = proton number

Electron number = 17

Mass number = Neutron + proton

Neutron = Mass number - proton

Neutron = 37 - 17

Neutron number = 20

icc, international association for cereal chemistry

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.