In the accompanying phase diagram, a solid can be present at combinations of tem

Question

In the accompanying phase diagram, a solid can be present at combinations of temperature and pressure corresponding to which of the following points? a0 B ony b) A, B, G c) A, B, C, and G d) A and B only e) A, B, C A and B only Which of the following substances has London Dispersion forces as the only intermolecular force? a)H_2O b)NH_3 c) CH_3CH_2OH d)C_2H_4 e) KBr Which of the following substances should have the highest melting point? a)CO_2 b) SrS c) Kr d) F_2 e) CaO Determine the vapor pressure (in mmHg) of a substance at 36 degree C, whose boiling point is 84 degree C at 760 mmHg and has a Delta H_vap of 22.1 kJ/mol. a) 239 mmHg b) 31.8 mmHG c) 41.8 mmHg d) 147 mmHg e) 98 mmHg

Explanation / Answer

1. Phase diagram represents the different states of matter under different conditions of temperature and pressure.This is same diagram as the phase diagrams of water and CO2.The first area represent the solid state,then the next area represent the liquid state and then comes the gaseous state.for example,here the point B represents solid state that is area in ACG represents solid region,the area in ACD represents liquid region that is the point F represents F region and the area GCD represents gaseous region that is the point E represents the gaseous region.The point C represents the critical point that is the point in which all the states are in equillibrium that means solid,liquid and gas coexist at this point.

so a) should be the correct option.point B represetns the solid state

2.Now here we can see that the first option is H2O which contains hydrogen bonding.the second option has N which is electronegative element that is it coontains hydrogen bonding.the third option has terminal OH again leading to Hydrogen bonding.The last option is KBr it is combination of electropositive and electronegative substances forming ionic bond.so the correct answer is (d) that is C2H4 contains london dispersion forces as main interactive forces.

3.Melting point depends on the type of bond present.(c) option is a nobel gas.so it is ruled out.now out of other 4 options,(b) and (e) are ionic bond compounds.So one of them must have highest melting point since ionic bond is strongest bond. now out of SrS and CaO, first of all calculate the charge on each ion.now both Sr2+ and Ca2+ have same charges.so we will compare their atomic sizes .

when we compare the size of Ca2+ and Sr2+,we find that the Ca ions are smaller than Sr ions.So smaller the size,larger is the binding force in it and stronger will be the bond formed.so (e) is the correct answer.that is CaO has highest melting point among them.

4.Using Clausius Clapeyron equation

we have ln(p1/p2)=<>H/R(1/T1-1/T2)

p1=760 torr, p2=? , <>H=22.1kj/mol=22100 J/mol , R=8.314 ,T1= 36+273=309 K, T2=84+273=357K

ln(760/p2)= 22100/8.314 (1/309-1/357)

ln(760/p2)=1.06

taking antilog on both sides,

p2=263 mmHg or 263 torr

Related Questions

Navigate

• Browse (All)
• Browse I
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.