# Basic Kinetic theory: How many molecules are there?

• Lagraaaange
In summary: I mixed up the conversion from cm^3 to m^3. The correct conversion should be 0.00167 m^3. So, using the correct value of V = 0.00167 m^3, the number of molecules in 1 cm^3 of vapor would be 3.3E23. Additionally, the number of vapor molecules striking each cm^2 of liquid surface per second would be 3.3E27. In summary, for a closed vessel containing liquid water at equilibrium with its vapor at 100C and 1 atm, with 1 gram of water vapor occupying 1670cm^3 and Hvap = 2250Jg^-1, there are
Lagraaaange

## Homework Statement

A closed vessel contains liquid water at equilibrium with its vapor at 100C and 1 atm. 1 gram of water vapor occupies 1670cm^3. Hvap = 2250Jg^-1. How many molecules are there per cm^3 of vapor?How many vapor molecules strike each cm^2 of liquid surface per second?

PV = NKT
Q = lm

## The Attempt at a Solution

N = PV/KT = 3.3E26 molecules of vapor
I used P = 1.013 E5 N m^-2
V = 16.7m^3
T = 373
Not sure how to get how much water there is.
Answers are: 2E19 molecules cm^-2 ; 3.3E23 impacts per second

How many water molecules are there in 1 gm of H2O? You are given the volume of 1 gm, so given these two, you should be able to calculate the number of molecules in 1 cm^3.

Lagraaaange said:

## Homework Statement

A closed vessel contains liquid water at equilibrium with its vapor at 100C and 1 atm. 1 gram of water vapor occupies 1670cm^3. Hvap = 2250Jg^-1. How many molecules are there per cm^3 of vapor?How many vapor molecules strike each cm^2 of liquid surface per second?

PV = NKT
Q = lm

## The Attempt at a Solution

N = PV/KT = 3.3E26 molecules of vapor
I used P = 1.013 E5 N m^-2
V = 16.7m^3
T = 373
Not sure how to get how much water there is.
Answers are: 2E19 molecules cm^-2 ; 3.3E23 impacts per second
BTW, 1670 cm3 ≠ 16.7 m3. Check your unit conversions again, since 1 m3 ≠ 100 cm3.

SteamKing said:
BTW, 1670 cm3 ≠ 16.7 m3. Check your unit conversions again, since 1 m3 ≠ 100 cm3.
Wow. Thanks

## 1. How do you define basic kinetic theory?

Basic kinetic theory is a scientific theory that explains the behavior and properties of particles in a gas, such as their motion and collisions with each other and with the container walls.

## 2. What is the relationship between temperature and the average kinetic energy of molecules?

According to the basic kinetic theory, temperature is directly proportional to the average kinetic energy of molecules. As the temperature increases, the average kinetic energy of molecules also increases.

## 3. How many molecules are there in a given amount of gas?

The number of molecules in a given amount of gas can be calculated using Avogadro's number, which is approximately 6.02 x 10^23 molecules per mole of gas.

## 4. How does the size of gas molecules affect their kinetic energy?

The size of gas molecules does not affect their kinetic energy. According to the basic kinetic theory, the average kinetic energy of molecules is only dependent on temperature, not on the size or type of molecules.

## 5. Can the basic kinetic theory be applied to all states of matter?

Yes, the basic kinetic theory can be applied to all states of matter, including solids, liquids, and gases. However, it is most commonly used to explain the behavior of gases due to their high molecular motion and relatively simple interactions.

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