Marzena Dzida, Mirosław Chorążewski

University of Silesia, Institute of Chemistry, Szkolna 9, Katowice

The effect of temperature and pressure

on the thermodynamic and acoustic properties of pentanols

at temperatures from (293 to 318) K and pressures up to 100 MPa

Investigated alcohol

CH3 CH2 CH2 CH2 CH2 OH

pentan-1-ol

CH3

CH3 CH2 C CH3

OH

2-methyl-2-butanol

CH3

CH3 CH2 CH CH2 OH

2-methyl-1-butanol

CH3 CH2 CH CH2 CH3

OH

pentan-3-ol

Aim:

Study of the influence of the structure of the alcohol

and the position of the hydroxyl group in the alcohol molecules

on temperature and pressure dependence of the thermodynamic properties

  

Physicochemical properties of isomeric pentanols at 298.15 K

2-methyl-1-butanol pentan-1-ol 2-methyl-2-butanol pentan-3-ol

K 153 153 10 85

b.p. / 0C 127.7 137.3 102.4 115.5

Hvap / kJ mol-1 54.1 56.9 51.5 52.9

Cp / J mol-1 K-1 213.88 208.14 247.60 253.39

/ kg m-3 815.02 810.84 804.29 817.18 r 15.63 15.13 5.78 13.35

/ D 1.88 1.65 1.70 1.64

gk 2.42 2.75 0.9 2.63

Ultrasonic speed measurements

temperature range 293 – 318 Kpressure range 0.1 – 100 MPamethod pulse-echo-overlap

accuracy  0.5 m s-1 (0.1 MPa); 1 m s-1 (p 0.1 MPa)

Density measurements

temperature range 293 – 318 Kpressure 0.1 MPamethod vibrating-tube densimeter (Anton Paar DMA 5000)

accuracy  0.05 kg m-3

Heat capacity measurements

temperature range 284 – 368.75 K pressure 0.1 MPamethod differential scanning calorimeter Micro DSC III

(University of Łódź)

accuracy  0.25 %

Experiment

High pressure ultrasonic cell

(1) pressure chamber (2) plug (3) transducer (4) reflector (5) acoustic tube (6) high pressure capillary(7) high pressure cable

Żak A., Dzida M., Zorębski M., Ernst S., A high pressure system for measurements of the speed of sound in liquids, Rev. Scient. Instr. (2000) 71, 1756-1768.

Dzida M., Chorążewski M., Zorębski M., Mańka R., Modification of a high pressure device for speed of sound measurements in liquids, J. de Physique IV (2006) 137, 203-207.

Speeds of sound in 2-methyl-1-butanol plotted against temperature at elevated

pressures: (●) 0.1 MPa, (▲) 30.39 MPa, (■) 60.79 MPa, () 101.32 MPa

290 300 310 3201100

1200

1300

1400

1500

1600

1700u

/ (m

· s-1

)

T / (K)

Determination of the pT data by the acoustic method

2

1

uS

Isothermal compressibility is related to isentropic one by the following relationship:

pS

pST C

T

C

VT

22

T

T p

1

pT C

T

up

2

2

1

pC

Tdp

u p

p

pΔ

1Δ

2

2

2

1

pT

TCp

p ΔΔ 2

where

Laplace formula:

Temperature dependences of the molar heat capacities of (▲) 2-methyl-1-butanol, (●) pentan-1-ol**, (■) 2-methyl-2-butanol*,

and () pentan-3-ol***at atmospheric pressure

*M. Dzida, P. Góralski, J. Chem. Thermodyn. 41 (2009) 402-413**M. Zábranský, V. Růžička and V. Majer, J. Phys. Chem. Ref. Data 19 (1990) 719–762

***C. A. Cerdeiriña, J. Troncoso, D. González-Salgado, G. García-Miaja, G. Hernández-Segura, D. Bessières, M. Medeiros, L. Romaní and M. Costas, J. Phys. Chem. B 111 (2007) 1119–1128

275 300 325 350 375180

200

220

240

260

280

300

320

T /(K)

Cp /

(J· m

ol-1

· K

-1)

Isobaric molar heat capacities as function of pressure of 2-methyl-1-butanol at () 293.15 K and (Δ) 318.15 K,

pentan-1-ol* at (●) 293.15 K and (○) 318.15 K, 2-methyl-2-butanol* at (■) 293.15 K and (□) 318.15 K,

and pentan-3-ol** at () 293.15 K and () 318.15 K (calorimetric measurement) *M. Dzida, J. Chem. Eng. Data (2009) in press

**C. A. Cerdeiriña, J. Troncoso, D. González-Salgado, G. García-Miaja, G. Hernández-Segura, D. Bessières, M. Medeiros, L. Romaní and M. Costas, J. Phys. Chem. B 111 (2007) 1119–1128

0 20 40 60 80 100190

205

220

235

250

265

280

p / (MPa)

Cp /

(J· m

ol-1

· K

-1)

Isobaric thermal expansion of (▲) 2-methyl-1-butanol, (●) pentan-1-ol*, (■) 2-methyl-2-butanol*, and () pentan-3-ol** at 303.15 K

*M. Dzida, J. Chem. Eng. Data 54 (2009) 1034-1040**Calculated from densities reported by D. González-Salgado, J. Troncoso, F. Plantier, J. L. Daridon, D. Bessières,

J. Chem. Thermodyn. 38 (2006) 893-899

0 20 40 60 80 1000.6

0.7

0.8

0.9

1.0

1.1

1.2

p / (MPa)

p ·

10

3/

(K-1

)

Isothermal compressibility of () 2-methyl-1-butanol, (●) pentan-1-ol*, (■) 2-methyl-2-butanol*, and () pentan-3-ol** at 303.15 K

*M. Dzida, J. Chem. Eng. Data 54 (2009) 1034-1040**D. González-Salgado, J. Troncoso, F. Plantier, J.L. Daridon, D. Bessières, J. Chem. Thermodyn. 38 (2006) 893-899.

0 20 40 60 80 1000.4

0.5

0.6

0.7

0.8

0.9

1.0

1.1

1.2

p / (MPa)

T ·

10

9/

(Pa-1

)

pTp

TpVS

TVU

pVTT

int

pT

pT

p

int

Internal pressure

pC

T

uTp

p

pp

12

2int1

Internal pressure is related to a work of intermolecular forces that accompany the change of volume.

315

320

325

330

335

340

345

350

355

360

365

370

0 20 40 60 80 100p / MPa

p in

t · 1

0 -6

/ (P

a )

280

285

290

295

300

305

310

315

0 20 40 60 80 100p / MPa

p in

t · 1

0 -6

/ (P

a )

Pressure dependence of internal pressure

(●) 293.15 K; (○) 298.15 K; (■) 303.15 K; (□) 308.15 K; (▲) 313.15 K; (Δ) 318.15 K() 323.15 K; () 333.15 K; (+) 343.15 K; (ӿ) 353.15 K; (—) 363.15 K; (-) 368.15 K

pentan-1-ol 2-methyl-2-butanol

2-methyl-1-butanolpentan-3-ol

0 20 40 60 80 100300

310

320

330

340

350

360

370

380

p / MPa

p in

t · 1

0 -6/

(Pa)

0 20 40 60 80 100300

310

320

330

340

350

360

370

380

p / MPa

p in

t · 1

0 -6

/ (P

a)

0 20 40 60 80 100280

285

290

295

300

305

310

315

320

p / MPa

p in

t · 1

0 -6/

(Pa)

Summary

The effect of pressure on isobaric heat capacity and isobaric thermal expansion for 2-methyl-1-butanol and pentan-1-ol is smaller than that for 2-methyl-2-butanol and pentan-3-ol and for isothermal compressibility this effect is the highest for 2-methyl-2-butanol

Heat capacity, isobaric thermal expansion, and isothermal compressibility

For 2-methyl-1-butanol, pentan-1-ol, and pentan-3-ol the internal pressure as function of pressure shows maximum.

For 2-methyl-2-butanol, the internal pressure increases with increasing pressure.

Internal pressure

For 2-methyl-2-butanol, pentan-1-ol, and pentan-3-ol the crossing points of the isotherms of internal pressure are observed.

For 2-methyl-2-butanol, pentan-1-ol, and pentan-3-ol the internal pressure decreases with increasing temperature at pressures up to the crossing point and then it increases with the increase of temperature.

For 2-methyl-1-butanol the internal pressure increases with increasing temperature.