Chem 2B

Flask A has a volume of 0.50 L and contains 50 g of a volatile liquid. Flask B has a volume of 1.0 L and contains 25 g of the same liquid. BOth flasks are closed and both are at 30 degrees celcius. the ration of the VP of the liquid in flask A to that in flask b is

1 : 1

What is an example of a closed system?

A bottle with a cap on it

Work is negative value when

A gas is given off during a chemical reaction

The enthalpy of vaporization of ammonia is

A positive number

Where does the process of deposition occur on a phase diagram?

Below the triple point

the standard enthalpy of formation is zero for all the following compounds: C (graphite) Na O2 Br2 Hg

Br2

What liquid would be most volatile?

CH3 CH2 CH2 CH2 CH2 CH2 H

A gas can be liquefied only at temperatures below the

Critical temperature

What is true about the critical point?

Density of the liquid phase and vapor phase are equal. The surface tension of the liquid approaches zero. The CP is the highest point on a VP curve

The concentration unity of molality is preferred over molarity because..

Molality doesn't change as temperature changes

What are some network covalent solid of carbon?

Molecular

A solution of salt water is heated and vapor pressure is seen leaving the solution. What is the composition of the vapor?

Pure water

Name crystal structure, CN, and # atom

SCC= 1 atom & 6CN BCC = 2 atom & 8CN FCC & CUBic closed= 4 atom & 12CN

A atmospheric pressure and room temperature, CO2 sublimes. If CO2 is put in a closed container under these conditions, what phases will exist while the sublimation is occurring?

Solid + Vapor

The solution in which the rate of crystallization will exceed that of the solution is called

Supersaturated

The vapor pressure of a solution changes as

Temperature changes

Under which of the following conditions will vaporization be maximized?

Weak forces between molecules, high kinetic energy, large surface area

A solution is ideal when

all intermolecular forces of attraction are the same, resulting in no net enthalpy change when the solution is formed from its components

A substance will sublime rather than melt if

its triple point occurs at a pressure above atm

What structure has the lowest density? (i.e. unit cell having least atoms?

simple cubic

The phenomenon in which a steel needle can, with proper care, be made to float on the surface of some water illustrates a property of liquids known as

surface tension

When a liquid is in equilibrium with its vapor in a closed container

the rate at which molecules from the liquid phase enter the gas phase exactly equals the rate at which molecules from gas phase pass into the liquid phase

enthalpy is defined as

the sum of the internal energy and the pressure-volume of a system

the enthalpy of condensation is equal to, but the opposite in sign from the enthalpy of

vaporization

The property of a liquid that measures its resistance to flow is called

viscosity

The slope of the fusion curve (curve separating th solid and liquid phases in a phase diagram) is negative for which compound?

water

What gives a decrease in the change of the internal energy of a system?

work done by system and heat released by system