What is 4.2 moles of lithium fluoride are dissolved in 200 lliliters of solution in molarity?

21 mol·L⁻¹

Step-by-step explanation:

Data:

n = 4.2 mol

V = 200 mL

Calculation:

c = moles/litres = n/V

V = 200 mL     Convert to litres

V = 200 mL ×(1 L/1000 mL)

V = 0.200 L

c = 4.2/0.200

c = 21 mol·L⁻¹

Note: This is an impossible value. Even at 100 °C, the solubility of NaF is only about 2 mol·L⁻¹.

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.