The enthalpy of vaporization (( \Delta H_{vap} )) is the amount of heat energy required to convert a liquid into a gas at its boiling point at a constant pressure. It represents the energy needed to overcome the intermolecular forces holding the liquid molecules together and allow them to escape into the gas phase.
The formula to calculate the mass of liquid boiled by 1 kJ of energy is: mass = 1 kJ / delta Hvap. ΔHvap is the molar enthalpy of vaporization, which is the amount of energy required to vaporize one mole of a substance. By dividing the energy input (1 kJ) by the enthalpy of vaporization, you can determine the mass of liquid that will be vaporized.
Grams liquid × mol/g × Hvap
1kJ x 1/deltaHvap x g/mol liquid.
The vapor pressure of water at 50ºC will be greater than that at 10ºC because of the added energy and thus greater movement of the water molecules. If one knows the ∆Hvap at a given temperature, one can calculate the vapor pressure at another temperature. This uses the Clausius-Clapeyron (sp?) equation. It turns out the vapor pressure of water at 10º is 9.2 mm Hg, and that at 50º is 92.5 mm Hg.
If you assume that the density of sweat is the same as that of water (1g/ml) and that the specific heat of sweat is the same as that of water (4.184 J/g/deg), then one can estimate the heat required to evaporate 7.24 ml of sweat at 25 degrees Cheat to raise 7.24 ml from 25º to 100º = q = mC∆T = (7.24g)(4.184 J/g/deg)(75deg) = 2272 J heat to evaporate 7.24 ml = q = m∆Hvap = (7.24g)(2260 J/g) = 16,362 J Total heat = 2272 J + 16,362 J = 18,634 J = 18.6 kJ
The formula to calculate the mass of liquid boiled by 1 kJ of energy is: mass = 1 kJ / delta Hvap. ΔHvap is the molar enthalpy of vaporization, which is the amount of energy required to vaporize one mole of a substance. By dividing the energy input (1 kJ) by the enthalpy of vaporization, you can determine the mass of liquid that will be vaporized.
1kJ x 1/Hvap x g/mol liquid
Grams liquid × mol/g × Hvap
The latent heat of vaporization (Hvap) is used to calculate the mass of liquid boiled by 1 kJ of energy using the formula: mass = energy / Hvap. This formula helps determine the amount of liquid that can be converted to vapor with a given amount of energy input.
Water vapor pressure can be calculated using the Clausius-Clapeyron equation, which relates vapor pressure to temperature. The equation is: ln(P2/P1) (Hvap/R)(1/T1 - 1/T2), where P1 and P2 are the vapor pressures at temperatures T1 and T2, Hvap is the heat of vaporization, and R is the gas constant.
1kJ x 1/deltaHvap x g/mol liquid.
To cool 10.0g of water from steam at 133.0°C to liquid at 53.0°C, you would need to pass through three phases: vapor to liquid, cool the liquid to 100°C, then finally cool it further to 53.0°C. The energy removed can be calculated using the specific heat capacity of water, enthalpy of vaporization, and heat of fusion, taking into account the temperature changes.
The density of water @ 100oC (boiling point) is about 0.958 g/ml. First we need to convert the 155 ml to mass by multiply by the density.155 ml * (0.958 g/ml) = 148.49 gramsNext convert the grams to moles by dividing by the molecular weight of water, which is 18 g/mol:148.49 grams /(18 g/mol) = 8.25 mol of H2OFinally multiply the moles of water by the heat of vaporization (Hvap) to get the final answer:8.25 mol * (40.7 kJ/mol) = 335.775 kJ
Grams liquid × mol/g × Hvap
It's called the melting point.
This would be a fairly simple experiment to do. You place your water in a chamber which is pressurized (or de-pressurized) to the desired degree of pressure, then slowly heat it with a Bunsen burner until it starts to boil; a thermomenter in the water will then tell you the temperature. If you just want the information, and don't want to do the experiment yourself, information about the boiling and freezing point of water at all different temperatures and pressures is given in what is known as a phase diagram. This can be found by way of Google under "water phase diagram" or in the Handbook of Physics and Chemistry.
The Hvap is usually given as J/g or J/mole for example. Let's say you have it in J/g. For water this is about 2260 J/g, meaning it takes 2260 joules to vaporize 1 g of water. Set up an equation using dimensional analysis: 1 kJ x 1000 J/kg x 1 g/2260 J = 0.44 g