DAT Question of the Day

Correct Answer: D. it increases, then becomes constant.

A pressure cooker fixes the atmospheric pressure to be higher than normal. In order for a liquid to boil, the vapor pressure inside of the container must be at least equal to the atmospheric pressure. For higher atmospheric pressures, like in a pressure cooker, the vapor pressure must also increase. Therefore, it takes longer for the vapor pressure of the gas to accumulate, leaving the liquid to become hotter and hotter. Once the boiling point is reached, the liquid is hotter than normal, cooking the food faster. Once the vapor pressure equals the environmental pressure of the pressure cooker, it remains constant. At this point the liquid is boiling and the vapor pressure of the liquid is equal to the atmospheric pressure of the pressure cooker. In this case, the only answer option that aligns correctly to what occurs in a pressure cooker is [D].

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Correct Answer: C. A pointer on a meter or surface of a liquid in a buret or pipette is not observed from directly straight on.

All options are common laboratory errors, but Parallax Error may occur when a pointer on a meter or surface of a liquid in a buret or pipette is not observed from directly straight on. If they are observed from above or below then the liquid surface or pointer will not be seen to line up with the scale.

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Correct Answer: A. High entropy, exothermic reactions with a low activation energy.

TNT explosions are very fast reactions (the lower the activation energy the less a reaction is impeded) involving the production of enormous quantities of heat (exothermic) and gaseous products (the production of hot gases from a solid explosive dramatically increases the disorder of the system, thus high entropy).

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Correct Answer: E. Volumetric

• Beaker: holds liquids, should not be used for accurate measurement.
• Buret: accurately measures unknown volumes up to 50.00 mL.
• Volumetric Pipette: accurately measures known small volumes like; 5.00 ml, 10.00 mL, 20.00 mL, 25.00 mL and 50.00 mL.
• Measuring cylinder: good for measuring volumes up to a 2 L, but not as accurately as the…
• Volumetric flask: specifically prepared to measure larger known volumes with an accuracy of 1 mL in a Liter.

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