Unit 3.3 Flashcards
what would the structure be of a solid crystalline
three-dimensional
what would you call it when a solid does not have a regular, orderly arrangement
amorphous
what formula do you use when
“calculate the value of the molar mass of the known gas”
PV=nRT
interpret PV=nRT
pressurevolume=moles.0821*temp
why does pressure decrease as temp decreases
bc as temp decreases, theres less bouncing on the walls so the pressure is decreasing
molar mass=
g of substance/moles
percent error formula
actual-theoretical/ actual *100
justify why there was a percent error
1-the flask was incompletely flushed with CO2(g), resulting in some dry air remaining in the flask
the dry air has less mass than CO2 so that’s why our number is less than it should be
Justify why there was a percent error
2-the temp of the air was 23C but the temp of the CO2 was lower than the reported 23C
incorrect bc if the temp decreased that means the volume decreases so density increases which also means the mass would increase. The mass of the gas would be too high
justify why there was a percent error:
1- The flask was incompletely flushed with CO2(g), resulting in some dry air remaining in the flask
correct bc dry air has less mass thatn CO2 so thats why the theortical number is less than it should be
as temp decreases, pressure…
decreases and vise versa
how could you tell if the volume of a rigid flask is 843mL at 23 degrees C without calculations
pour to flask into a 1000mL granulated cylinder and record the volume to see if you were correct
mm equation
mm=DRT/P
steps to “find partial pressure” when given total torr
1) find moles first
1st element:
g/mass=mols
2nd element:
g/mass=mols
2) add both for total moles
3) divide each individual mol/ total moles
=that is called P
4) each: P*element=P * total torr
Steps to find partial pressure when not given total
1) find moles for both elements
g/mass
add those together to get total pressure
2) so PV=nRT plug in total pressure for n
3) do individual PV=nRT and divide that by total
find g in of one element from a mixture steps
1) find moles for element with given grams
g/mass
2) find moles for other element using PV=nRT
3)subtract given-unkown
4) convert moles to g
“find the mole fraction”
moles/total moles
just do the partial pressure/total pressure
How to convert Temp to Kelvin
T+273.15
How to convert atm to mmHg
P*760
How to convert mmHg to atm
/760
What is the constant R for atm
.0821
What is the constant R for tarr
62.36
The stopcock connecting a 4.43 L bulb containing methane gas at a pressure of 7.28 atm, and a 5.10 L bulb containing carbon dioxide gas at a pressure of 2.46 atm, is opened and the gases are allowed to mix. Assuming that the temperature remains constant, the final pressure in the system is
atm.
what formula would you use to answer this question
Ptotal=(p1v1)+(p2v2) / (v1+v2)
A helium-filled weather balloon has a volume of 703 L at 18.9°C and 759 mmHg. It is released and rises to an altitude of 2.40 km, where the pressure is 627 mmHg and the temperature is 3.9°C.
The volume of the balloon at this altitude is ____ L
what formula would you use to answer this question
(p1v1) (p2v2)
———- = ———–
T1 T2
A 1.59 mol sample of gas is confined in a 38.0 liter container at 18.0 °C.
If 1.59 mol of gas is added holding the volume and temperature constant, the average kinetic energy of the total system will
decrease
remain the same
increase
not enough information to answer the questions
remain the same
The average kinetic energy in a gas sample depends only on the temperature, and not on the identity or the amount of the gas. Since the temperature is constant, the average kinetic energy is constant.
A 1.66 mol sample of N2 gas is confined in a 42.1 liter container at 35.7 °C.
If the amount of gas is increased to 2.49 mol, holding the volume and temperature constant, the pressure will increase because:
(Select all that apply.)
a) With more molecules per unit volume, the molecules hit the walls of the container more often.
b) With higher average speeds, on average the molecules hit the walls of the container with more force.
c) With more molecules in the container, the molecules have higher average speeds.
d) As the number of molecule-wall collisions increases, the force per collision decreases.
a) With more molecules per unit volume, the molecules hit the walls of the container more often.
mass in relation to speed
more mass=slower
2 containers at the same temperature
1st- bigger volume, less molecules
2nd- smaller volume, more molecules
which one is faster
they will have the same speed
2 containers
1st- bigger volume, less molecules, lower temp
2nd- smaller volume, more molecules, higher temp
2nd one will be faster
Which of the following statements is true for real gases?
Choose all that apply.
a) Attractive forces between molecules cause a decrease in pressure compared to the ideal gas.
b) The volume occupied by the molecules can cause a decrease in pressure compared to the ideal gas.
c) As molecules increase in size, deviations from ideal behavior become more apparent at relatively high pressures.
d) As attractive forces between molecules increase, deviations from ideal behavior become more apparent at relatively high temperatures.
a) Attractive forces between molecules cause a decrease in pressure compared to the ideal gas.
c) As molecules increase in size, deviations from ideal behavior become more apparent at relatively high pressures.
In general, real gases behave most ideally at ____ pressures and ___ temperatures.
low pressures and high temperatures
Which of the following statements is true for ideal gases, but is not always true for real gases?
Choose all that apply.
a) The size of the molecules is unimportant compared to the distances between them.
b) Pressure is caused by molecule-wall collisions.
c) There are no attractive forces between molecules.
d) Molecules are in constant random motion.
a) The size of the molecules is unimportant compared to the distances between them.
c) There are no attractive forces between molecules.
