# Question Moist air at 1 atmosphere and 30°C has a relative humidity of 50%. What is the humidity ratio (w) of the air? 0.0212 0.0425 O 0.0136 0.50 Liquid water is injected into a sealed, thermally insulated container of dry air, so that it collects at the base. It is observed, over time, to completely evaporate, with the moist air now at a slightly cooler temperature. Which of the following is the correct explanation. Heat generated by the evaporation process drives further evaporation. So ALL of the water must eventually evaporate. In a sealed container the water could not have possibly evaporated. There must either be heat input into the container from an external source, or a leak in the container allowing vapour to escape. This cannot happen. At equilibrium, condensation and evaporation occur at equal rates, so some water will always remain. The water will tend find its equilibrium as a liquid/vapour mix at a saturated temperature/pressure combination. However, if there is insufficient liquid water for the vapour's partial pressure to reach its saturation value, it will completely evaporate. And evaporative cooling occurs as a consequence. If a psychrometric mixture at 1 bar is comprised of water/air mixture where the mass ratio of water to air is 1%, what is the partial pressure of the air? O 0.947 bar 0.995 bar 0.972 bar 0.984 bar Which of the follow statements best describes the Dalton model for moist air? Moist air is dry air that contains small "atomised" droplets of liquid water, all at a common temperature. Dry air and water vapour coexist as ideal gases - sharing common volume and temperature, but contributing partial pressures. Moist air may be considered as a saturated liquid-vapour mix of water, as the energy density of the water component is far greater than the air. Dry air and water vapour coexist as ideal gases - sharing common pressure and temperature, but contributing partial volumes. Exhaust from a car may be very crudely modeled as a water/air ideal gas mixture at 1 atmosphere pressure. If exhaust vapour condenses at 55°C, what is its humidity ratio (w)? O 0.1576 0.1146 0.3230 The question does not make sense. Car exhaust is an ideal gas, and so does not condense.

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Transcribed Image Text: Moist air at 1 atmosphere and 30°C has a relative humidity of 50%. What is the humidity ratio (w) of the air? 0.0212 0.0425 O 0.0136 0.50 Liquid water is injected into a sealed, thermally insulated container of dry air, so that it collects at the base. It is observed, over time, to completely evaporate, with the moist air now at a slightly cooler temperature. Which of the following is the correct explanation. Heat generated by the evaporation process drives further evaporation. So ALL of the water must eventually evaporate. In a sealed container the water could not have possibly evaporated. There must either be heat input into the container from an external source, or a leak in the container allowing vapour to escape. This cannot happen. At equilibrium, condensation and evaporation occur at equal rates, so some water will always remain. The water will tend find its equilibrium as a liquid/vapour mix at a saturated temperature/pressure combination. However, if there is insufficient liquid water for the vapour's partial pressure to reach its saturation value, it will completely evaporate. And evaporative cooling occurs as a consequence. If a psychrometric mixture at 1 bar is comprised of water/air mixture where the mass ratio of water to air is 1%, what is the partial pressure of the air? O 0.947 bar 0.995 bar 0.972 bar 0.984 bar Which of the follow statements best describes the Dalton model for moist air? Moist air is dry air that contains small "atomised" droplets of liquid water, all at a common temperature. Dry air and water vapour coexist as ideal gases - sharing common volume and temperature, but contributing partial pressures. Moist air may be considered as a saturated liquid-vapour mix of water, as the energy density of the water component is far greater than the air. Dry air and water vapour coexist as ideal gases - sharing common pressure and temperature, but contributing partial volumes. Exhaust from a car may be very crudely modeled as a water/air ideal gas mixture at 1 atmosphere pressure. If exhaust vapour condenses at 55°C, what is its humidity ratio (w)? O 0.1576 0.1146 0.3230 The question does not make sense. Car exhaust is an ideal gas, and so does not condense.
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Transcribed Image Text: Moist air at 1 atmosphere and 30°C has a relative humidity of 50%. What is the humidity ratio (w) of the air? 0.0212 0.0425 O 0.0136 0.50 Liquid water is injected into a sealed, thermally insulated container of dry air, so that it collects at the base. It is observed, over time, to completely evaporate, with the moist air now at a slightly cooler temperature. Which of the following is the correct explanation. Heat generated by the evaporation process drives further evaporation. So ALL of the water must eventually evaporate. In a sealed container the water could not have possibly evaporated. There must either be heat input into the container from an external source, or a leak in the container allowing vapour to escape. This cannot happen. At equilibrium, condensation and evaporation occur at equal rates, so some water will always remain. The water will tend find its equilibrium as a liquid/vapour mix at a saturated temperature/pressure combination. However, if there is insufficient liquid water for the vapour's partial pressure to reach its saturation value, it will completely evaporate. And evaporative cooling occurs as a consequence. If a psychrometric mixture at 1 bar is comprised of water/air mixture where the mass ratio of water to air is 1%, what is the partial pressure of the air? O 0.947 bar 0.995 bar 0.972 bar 0.984 bar Which of the follow statements best describes the Dalton model for moist air? Moist air is dry air that contains small "atomised" droplets of liquid water, all at a common temperature. Dry air and water vapour coexist as ideal gases - sharing common volume and temperature, but contributing partial pressures. Moist air may be considered as a saturated liquid-vapour mix of water, as the energy density of the water component is far greater than the air. Dry air and water vapour coexist as ideal gases - sharing common pressure and temperature, but contributing partial volumes. Exhaust from a car may be very crudely modeled as a water/air ideal gas mixture at 1 atmosphere pressure. If exhaust vapour condenses at 55°C, what is its humidity ratio (w)? O 0.1576 0.1146 0.3230 The question does not make sense. Car exhaust is an ideal gas, and so does not condense.