Week 7 Quiz

A 15 g piece of iron [c_p = 25.09 J/(mol·℃)] is heated to a temperature of 95℃ and placed into a bucket containing 4.5 gal of water [c_p = 75.38 J/(mol·℃)], initially at 25℃. Eventually,

• the water will be warmer than the iron

• the iron will be warmer than the water

• the iron will be colder than the water

• the iron and the water will be at the same temperature

• the temperature will be the average of 98℃ and 25℃

Tags

NGSS.HS-PS3-1

NGSS.HS-PS3-4

For which of the following is the standard enthalpy of formation NOT equal to zero?

• C(s, diamond)

• Na(s)

• H2(g)

• Br2(l)

• Al(s)

Which of the following statements about energy, systems, and surroundings is NOT true?

• The system can be a chemical reaction that occurs in a sample of matter

• The surroundings experience the same energy change as the system in order to keep the total energy in the universe constant

• The system is the part of the universe that is the focus of thermochemical study

• The surroundings can provide thermal energy to the system

• The system can do work on the surroundings

Tags

NGSS.HS-PS3-4

A solution is prepared by mixing 50.00 g of methanol (CH₃OH, 32.04 g/mol) with 50.00 g of ethanol (CH₃CH₂OH, 46.07 g/mol). Use the following data to determine the vapor pressure of this solution at 20℃. Vapor Pressure at 20℃
Methanol = 92 torr

Ethanol = 45 torr

• 69 torr

• 57 torr

• 79 torr

• 72 torr

• 83 torr

Which statement below regarding vapor pressure is NOT correct?

• Vapor pressure is an intensive property

• The substance with the stronger intermolecular forces has the lower vapor pressure

• Vapor pressure increases with increasing temperature

• Pure water has a higher vapor pressure at a given temperature than seawater

• A nonvolatile solute increases the vapor pressure of the solvent