Unit 3.3

Question 1

what would the structure be of a solid crystalline

Answer 1

three-dimensional

Question 2

what would you call it when a solid does not have a regular, orderly arrangement

Answer 2

amorphous

Question 3

what formula do you use when
“calculate the value of the molar mass of the known gas”

Answer 3

PV=nRT

Question 4

interpret PV=nRT

Answer 4

pressurevolume=moles.0821*temp

Question 5

why does pressure decrease as temp decreases

Answer 5

bc as temp decreases, theres less bouncing on the walls so the pressure is decreasing

Question 6

molar mass=

Answer 6

g of substance/moles

Question 7

percent error formula

Answer 7

actual-theoretical/ actual *100

Question 8

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

Answer 8

the dry air has less mass than CO2 so that’s why our number is less than it should be

Question 9

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

Answer 9

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

Question 10

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

Answer 10

correct bc dry air has less mass thatn CO2 so thats why the theortical number is less than it should be

Question 11

as temp decreases, pressure…

Answer 11

decreases and vise versa

Question 12

how could you tell if the volume of a rigid flask is 843mL at 23 degrees C without calculations

Answer 12

pour to flask into a 1000mL granulated cylinder and record the volume to see if you were correct

Question 13

mm equation

Answer 13

mm=DRT/P

Question 14

steps to “find partial pressure” when given total torr

Answer 14

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

Question 15

Steps to find partial pressure when not given total

Answer 15

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

Question 16

find g in of one element from a mixture steps

Answer 16

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

Question 17

“find the mole fraction”

Answer 17

moles/total moles

just do the partial pressure/total pressure

Question 18

How to convert Temp to Kelvin

Answer 18

T+273.15

Question 19

How to convert atm to mmHg

Answer 19

P*760

Question 20

How to convert mmHg to atm

Answer 20

/760

Question 21

What is the constant R for atm

Answer 21

.0821

Question 22

What is the constant R for tarr

Answer 22

62.36

Question 23

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

Answer 23

Ptotal=(p1v1)+(p2v2) / (v1+v2)

Question 24

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

Answer 24

(p1v1) (p2v2)
———- = ———–
T1 T2

Question 25

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

Answer 25

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.

Question 26

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.

Answer 26

a) With more molecules per unit volume, the molecules hit the walls of the container more often.

Question 27

mass in relation to speed

Answer 27

more mass=slower

Question 28

2 containers at the same temperature

1st- bigger volume, less molecules
2nd- smaller volume, more molecules

which one is faster

Answer 28

they will have the same speed

Question 29

2 containers

1st- bigger volume, less molecules, lower temp
2nd- smaller volume, more molecules, higher temp

Answer 29

2nd one will be faster

Question 30

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.

Answer 30

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.

Question 31

In general, real gases behave most ideally at ____ pressures and ___ temperatures.

Answer 31

low pressures and high temperatures

Question 32

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.

Answer 32

a) The size of the molecules is unimportant compared to the distances between them.

c) There are no attractive forces between molecules.