# Chemistry

posted by .

You wish to know the enthalpy change for the formation of liquid PCl3 from the elements shown below.

P4(s) + 6 Cl2(g)--> 4 PCl3(l) ΔH°f = ?
The enthalpy change for the formation of PCl5 from the elements can be determined experimentally, as can the enthalpy change for the reaction of PCl3(l) with more chlorine to give PCl5(s).

P4(s) + 10 Cl2(g)--> 4 PCl5(s) ΔH°rxn= -1774.0 kJ

PCl3(l) + Cl2(g)--> PCl5(s) ΔH°rxn = -123.8 kJ
Use these data to calculate the enthalpy change for the formation of 1.50 mol of PCl3(l) from phosphorus and chlorine.

• Chemistry -

P4(s) + 10 Cl2(g)--> 4 PCl5(s) ΔH°rxn= -1774.0 kJ

PCl3(l) + Cl2(g)--> PCl5(s) ΔH°rxn = -123.8 kJ

Use eqn 1 as is. Multiply eqn 2 by 4 (multiply delta H rxn by 4 also), reverse it (change the sign of delta H x 4), and add to eqn 1. That will give you the reaction you want. Add the delta Hs to arrive at delta H for the desired reaction. That will be delta H for 4 moles of PCl3 and you change that to 1.50 moles PCl3.

## Similar Questions

1. ### Chemistry

Initially, 1.68 mol of PCl5(g) and 0.36 mol of PCl3(g) are in mixed in a 2.00 l container. It is later found that 1.44 mol of PCl5 are present when the system has reached equillibrium. Calculate the value of the equllibrium. This is …
2. ### Chemistry

You are given the following data. P4(s) + 6 Cl2(g) 4 PCl3(g) ΔH = -1225.6 kJ P4(s) + 5 O2(g) P4O10(s) ΔH = -2967.3 kJ PCl3(g) + Cl2(g) PCl5(g) ΔH = -84.2 kJ PCl3(g) + 1/2 O2(g) Cl3PO(g) ΔH = -285.7 kJ Calculate …
3. ### Chemistry

When a sample of PCl5(g) (0.02087 mol/L) is placed in 83.00 L reaction vessel at 491.0 °C and allowed to come to equilibrium the mixture contains 103.0 grams of PCl3(g). What is the equilibrium concentration (mol/L) of Cl2(g)?
4. ### CHEMISTRY

1.Calculate the enthalpy change (ΔHºrxn) for the following reaction: (The enthalpy of formation of aqueous sodium hydroxide is -469.60 kJ/mol. The enthalpy of formation of liquid water is -285.8 kJ/mol.) 2Na (s) + 2H2O (l) → …
5. ### CHEMISTRY

Equilibrium Equation with Partial Pressures PCl3(g) +Cl2(g) <-> PCl5(g)?
6. ### Chemistry

calculate the enthalpy change for: (enthalpy of formation of aqueous sodium hydroxide is -469.60 kJ/mol. enthalpy of formation of liquid water is -285.8 kJ/mol) 2Na + 2H2O = 2 NaOH + H2
7. ### Science

The following heats of formation are used to find the change in enthalpy for the formation of tin chloride in the following reaction Sn (s) + 2Cl2(g) --> SnCl4(l).Sn(s) + Cl2(g) --> Sn Cl2(l) DH = -186.2 kJSnCl2(s) + Cl2(g) --> …
8. ### chem

Given these two reactions, how do I calculate ΔH for the third one?
9. ### chemistry

The enthalpy of formation of C2H5OH is -238.7 kJ/mol. What information does this reveal about the bonds in the molecule?
10. ### Chemistry - Answer Check

The two common chlorides of Phosphorus, PCl3 and PCl5, both important in the production of other phosphorous compounds, coexist in equilibrium as shown in the balanced chemical reaction below: PCl3 (g) + Cl2 (g) <-----> PCl5 …

More Similar Questions