chem 2 lab final exam

which of the following are true? - a volumetric flask w/o a stopper is useless - a volumetric flask contains the volume it was calibrated for when it is filled to the base of its neck - a volumetric flask does not require mixing, because addition of the solvent mixes the solution - a volumetric flask should be inverted and swirled before use

-a volumetric flask w/o a stopper is useless - a volumetric flask should be inverted and swirled before use

what is the name of the band held device used to produce electricity in this lab?

Dc Generator

which of the following count as one electron domain? a) the four electrons in a double bond b) a lone pair of electrons c) the pair in a single bond

all of the above

the larger the "load" connected to the hand held device, the larger the amount of work the device must do. How does one assess how large the load is in this lab?

by how hard the handle is to turn

suppose a chemical reaction is initially at equilibrium, but then a change is made in the equilibrium system. to return to equilibrium the equilibrium position will shift so as to

counteract the change

non spontaneous reactions are reactions that do not automatically produce any product. how can products be made to form from a non spontaneous reaction?

doing work on a system can make a non-spontaneous reaction occur

a blank is a solution that should contain

everything that the sample contains except for the species to be determined

the volume occupied by air inside the flask is equal to the volume engraved on the flask? true/ false

false

the electronic geometry gives the "actual" shape of a molecule true/false

false- electronic geometry depends on the number of electron domains around a central atom

in this lab the volume of the erlenmeyer flask is measured by

filling the flask w water, then transferring the water to a graduated cylinder

according to le chateliers principle in which direction will equilibrium shift if products are removed

if products are removed, equilibrium will shift to favor the forward reaction

according to beers law, a plot of absorbance vs. concentration is

linear

the dumas method is used to determine the molar mass of a volatile liquid

molar mass

acetic acid is a weak acid. suppose 1 mole of acetic acid is placed in 1 L of water. in this solution dissociation of the acetic acid

occurs to only a small extent

according to le chateliers principle adding heat to a system is equivalent to

raising the temperature

an indication that vaporization of the unknown liquid is complete is that the

ring of liquid around the boiling stone disappears or stops changing

a cuvette is a

sample holder for measuring absorbance

in this lab when the NaSCN connect ration is increased the equilibrium constant

stays the same

the electronic geometry of PCl3 is?

tetrahedral

when the dissociation constant of a weak acid, Ka, is calculated for this lab, which one of the following is used in the final step of calculating Ka?

the equilibrium concentration of the weak acid

in this experiment 0.1 M HNO3 is used to dilute all the solutions because

the solution must be kept acidic to prevent Fe+3 from precipitating

suppose the pinch clamp on the flask assembly was not opened prior to heating the flask assembly in boiling water. which of the following is the most likely problem that this would create? - air inside the flask might be overheated - the stopper assembly might be forced out of the mouth of the flask - the temperature of the boiling water might be lowered - the temperature of the air inside the flask might be lowered

the stopper assembly might be forced out of the mouth of the flask

the molecular geometry of PCl3 is

trigonal pyramidal

electrical work is done by turning the crank of the hand held device. true/ false

true

which instrument is used to measure the amount of voltage produced from the reaction between a meta and an ionic compound

voltmeter

in this lab the inside of the flask must be absolutely dry before it is fitted w the stopper assembly and weighed. the main reason is that

when the ayer inside the flask vaporizes, it will displace the air in the flask during heating. then, when cooled down, the water will condense and too much water will be sucked into the flask