3 correct typo edited Feb 21 '14 at 0:40 Ross Millikan 7,96511521 For water and most solids/liquids, yes but very slightly. When you heat the water it expands, which does work against the surrounding pressure. At higher pressure, the expansion takes more work. For example, in heating water from $$10 C$$ to $$30 C$$, the density decreases from $$999.7026 \frac {kg}{m^2}$$$$999.7026 \frac {kg}{m^3}$$ to $$995.6502 \frac {kg}{m^2}$$$$995.6502 \frac {kg}{m^3}$$, so $$1 kg$$ of water expands by $$2.066\cdot10^{-6} m^3$$. At $$1 atm= 101325 \frac N{m^2}$$ this does $$0.209 J$$ of work and at $$3 atm$$ it would be three times this or $$0.627 J$$. By comparison, the energy to heat the water due to the temperature is about $$20000*4.183=83680 J$$ If you care about this level of accuracy, you need to see what conditions were used in your tables, and there may be other effects to consider. The difference over pressure should be reliable. For water and most solids/liquids, yes but very slightly. When you heat the water it expands, which does work against the surrounding pressure. At higher pressure, the expansion takes more work. For example, in heating water from $$10 C$$ to $$30 C$$, the density decreases from $$999.7026 \frac {kg}{m^2}$$ to $$995.6502 \frac {kg}{m^2}$$, so $$1 kg$$ of water expands by $$2.066\cdot10^{-6} m^3$$. At $$1 atm= 101325 \frac N{m^2}$$ this does $$0.209 J$$ of work and at $$3 atm$$ it would be three times this or $$0.627 J$$. By comparison, the energy to heat the water due to the temperature is about $$20000*4.183=83680 J$$ If you care about this level of accuracy, you need to see what conditions were used in your tables, and there may be other effects to consider. The difference over pressure should be reliable. For water and most solids/liquids, yes but very slightly. When you heat the water it expands, which does work against the surrounding pressure. At higher pressure, the expansion takes more work. For example, in heating water from $$10 C$$ to $$30 C$$, the density decreases from $$999.7026 \frac {kg}{m^3}$$ to $$995.6502 \frac {kg}{m^3}$$, so $$1 kg$$ of water expands by $$2.066\cdot10^{-6} m^3$$. At $$1 atm= 101325 \frac N{m^2}$$ this does $$0.209 J$$ of work and at $$3 atm$$ it would be three times this or $$0.627 J$$. By comparison, the energy to heat the water due to the temperature is about $$20000*4.183=83680 J$$ If you care about this level of accuracy, you need to see what conditions were used in your tables, and there may be other effects to consider. The difference over pressure should be reliable. 2 add info edited Feb 20 '14 at 16:09 Ross Millikan 7,96511521 For water and most solids/liquids, yes but very slightly. When you heat the water it expands, which does work against the surrounding pressure. At higher pressure, the expansion takes more work. For example, in heating water from $$10 C$$ to $$30 C$$, the density decreases from $$999.7026 \frac {kg}{m^2}$$ to $$995.6502 \frac {kg}{m^2}$$, so $$1 kg$$ of water expands by $$2.066\cdot10^{-6} m^3$$. At $$1 atm= 101325 \frac N{m^2}$$ this does $$0.209 J$$ of work and at $$3 atm$$ it would be three times this or $$0.627 J$$. By comparison, the energy to heat the water due to the temperature is about $$20000*4.183=83680 J$$ If you care about this level of accuracy, you need to see what conditions were used in your tables, and there may be other effects to consider. The difference over pressure should be reliable. For water and most solids/liquids, yes but very slightly. When you heat the water it expands, which does work against the surrounding pressure. At higher pressure, the expansion takes more work. For example, in heating water from $$10 C$$ to $$30 C$$, the density decreases from $$999.7026 \frac {kg}{m^2}$$ to $$995.6502 \frac {kg}{m^2}$$, so $$1 kg$$ of water expands by $$2.066\cdot10^{-6} m^3$$. At $$1 atm= 101325 \frac N{m^2}$$ this does $$0.209 J$$ of work and at $$3 atm$$ it would be three times this or $$0.627 J$$. By comparison, the energy to heat the water due to the temperature is about $$20000*4.183=83680 J$$ For water and most solids/liquids, yes but very slightly. When you heat the water it expands, which does work against the surrounding pressure. At higher pressure, the expansion takes more work. For example, in heating water from $$10 C$$ to $$30 C$$, the density decreases from $$999.7026 \frac {kg}{m^2}$$ to $$995.6502 \frac {kg}{m^2}$$, so $$1 kg$$ of water expands by $$2.066\cdot10^{-6} m^3$$. At $$1 atm= 101325 \frac N{m^2}$$ this does $$0.209 J$$ of work and at $$3 atm$$ it would be three times this or $$0.627 J$$. By comparison, the energy to heat the water due to the temperature is about $$20000*4.183=83680 J$$ If you care about this level of accuracy, you need to see what conditions were used in your tables, and there may be other effects to consider. The difference over pressure should be reliable. 1 answered Feb 20 '14 at 15:00 Ross Millikan 7,96511521 For water and most solids/liquids, yes but very slightly. When you heat the water it expands, which does work against the surrounding pressure. At higher pressure, the expansion takes more work. For example, in heating water from $$10 C$$ to $$30 C$$, the density decreases from $$999.7026 \frac {kg}{m^2}$$ to $$995.6502 \frac {kg}{m^2}$$, so $$1 kg$$ of water expands by $$2.066\cdot10^{-6} m^3$$. At $$1 atm= 101325 \frac N{m^2}$$ this does $$0.209 J$$ of work and at $$3 atm$$ it would be three times this or $$0.627 J$$. By comparison, the energy to heat the water due to the temperature is about $$20000*4.183=83680 J$$