Calculating the Pressure of a Bike Tire

Oct 13, 2025 by wbrum.org 19 views

The ideal gas law is a fundamental concept in chemistry that describes the behavior of gases under various conditions. It is a mathematical equation that relates the pressure, volume, and temperature of a gas. The ideal gas law is expressed as:

PV = nRT

Where:

P is the pressure of the gas in pascals (Pa)
V is the volume of the gas in cubic meters (m³)
n is the number of moles of gas
R is the gas constant in pascals per cubic meter per kelvin (Pa·m³/K)
T is the temperature of the gas in kelvin (K)

Calculating the Pressure of a Bike Tire

In this problem, we are given the number of moles of gas (0.94 moles) and the temperature (25°C). We need to calculate the pressure of the tire. To do this, we can rearrange the ideal gas law equation to solve for pressure:

P = nRT / V

We are given the number of moles (n) and the temperature (T), but we need to find the volume (V) of the tire. The volume of the tire can be calculated using the formula:

V = πr²h

Where:

r is the radius of the tire in meters (m)
h is the height of the tire in meters (m)

However, we are not given the radius or height of the tire. Instead, we are given the volume of the tire in liters (L). We can convert the volume from liters to cubic meters by multiplying by 0.001:

V = 4.0 L × 0.001 = 0.004 m³

Now that we have the volume, we can plug in the values into the ideal gas law equation:

P = nRT / V

We can use the gas constant (R) to convert the temperature from Celsius to Kelvin:

T = 25°C + 273.15 = 298.15 K

Now we can plug in the values:

P = 0.94 mol × 8.3145 J/mol·K × 298.15 K / 0.004 m³

P = 215,111.5 Pa

Converting the Pressure to a More Familiar Unit

The pressure we calculated is in pascals (Pa), but it is more common to express pressure in units such as pounds per square inch (psi) or atmospheres (atm). We can convert the pressure to psi by dividing by 6894.76:

P = 215,111.5 Pa ÷ 6894.76 = 31.2 psi

Conclusion

In this problem, we used the ideal gas law to calculate the pressure of a bike tire. We were given the number of moles of gas and the temperature, and we were able to calculate the pressure by rearranging the ideal gas law equation and plugging in the values. We also converted the pressure from pascals to psi for a more familiar unit.

PV = nRT

Where:

P is the pressure of the gas in pascals (Pa)
V is the volume of the gas in cubic meters (m³)
n is the number of moles of gas
R is the gas constant in pascals per cubic meter per kelvin (Pa·m³/K)
T is the temperature of the gas in kelvin (K)

The Importance of the Ideal Gas Law

The ideal gas law is a crucial concept in chemistry because it allows us to predict the behavior of gases under various conditions. It is used in a wide range of applications, from the design of gas tanks to the calculation of the pressure of a bike tire.

Real-World Applications of the Ideal Gas Law

The ideal gas law has many real-world applications. For example, it is used in the design of gas tanks to ensure that they can withstand the pressure of the gas inside. It is also used in the calculation of the pressure of a bike tire, as we saw in this problem.

Conclusion

In this article, we discussed the ideal gas law and its importance in chemistry. We also used the ideal gas law to calculate the pressure of a bike tire. We hope that this article has provided a clear understanding of the ideal gas law and its applications.

References

CRC Handbook of Chemistry and Physics, 97th ed. (2016)
Chemistry: The Central Science, 14th ed. (2018)
The Ideal Gas Law, Wikipedia (2022)

Q: What is the ideal gas law?

A: The ideal gas law is a fundamental concept in chemistry that describes the behavior of gases under various conditions. It is a mathematical equation that relates the pressure, volume, and temperature of a gas. The ideal gas law is expressed as:

PV = nRT

Where:

P is the pressure of the gas in pascals (Pa)
V is the volume of the gas in cubic meters (m³)
n is the number of moles of gas
R is the gas constant in pascals per cubic meter per kelvin (Pa·m³/K)
T is the temperature of the gas in kelvin (K)

Q: How is the ideal gas law used in real-world applications?

A: The ideal gas law has many real-world applications. For example, it is used in the design of gas tanks to ensure that they can withstand the pressure of the gas inside. It is also used in the calculation of the pressure of a bike tire, as we saw in this problem.

Q: What is the gas constant (R)?

A: The gas constant (R) is a physical constant that relates the pressure, volume, and temperature of a gas. It is expressed in units of pascals per cubic meter per kelvin (Pa·m³/K).

Q: How is the temperature converted from Celsius to Kelvin?

A: To convert the temperature from Celsius to Kelvin, we add 273.15 to the temperature in Celsius. For example, if the temperature is 25°C, we can convert it to Kelvin by adding 273.15:

T = 25°C + 273.15 = 298.15 K

Q: How is the pressure calculated using the ideal gas law?

A: To calculate the pressure using the ideal gas law, we can rearrange the equation to solve for pressure:

P = nRT / V

We can then plug in the values for the number of moles (n), the gas constant (R), the temperature (T), and the volume (V) to calculate the pressure.

Q: What is the volume of the bike tire in cubic meters?

A: The volume of the bike tire is given as 4.0 L. We can convert this to cubic meters by multiplying by 0.001:

V = 4.0 L × 0.001 = 0.004 m³

Q: What is the pressure of the bike tire in pascals?

A: To calculate the pressure of the bike tire, we can plug in the values for the number of moles (n), the gas constant (R), the temperature (T), and the volume (V) into the ideal gas law equation:

P = 0.94 mol × 8.3145 J/mol·K × 298.15 K / 0.004 m³

P = 215,111.5 Pa

Q: How is the pressure converted from pascals to psi?

A: To convert the pressure from pascals to psi, we can divide by 6894.76:

P = 215,111.5 Pa ÷ 6894.76 = 31.2 psi

Q: What is the final answer to the problem?

A: The final answer to the problem is 31.2 psi.

Conclusion

In this Q&A article, we discussed the ideal gas law and its importance in chemistry. We also used the ideal gas law to calculate the pressure of a bike tire. We hope that this article has provided a clear understanding of the ideal gas law and its applications.

References

CRC Handbook of Chemistry and Physics, 97th ed. (2016)
Chemistry: The Central Science, 14th ed. (2018)
The Ideal Gas Law, Wikipedia (2022)