Standard temperature and pressure (STP) is a crucial concept in gas calculations, providing a reference point for various scientific measurements. At STP, the temperature is defined as 0 degrees Celsius, which is equivalent to 273.15 Kelvin. It is important to use Kelvin for gas calculations, as it is the absolute temperature scale. Additionally, the pressure at STP is set at 1 atmosphere (atm). Therefore, when referring to STP, remember that it signifies a temperature of 273.15 K and a pressure of 1 atm, which are essential for accurately applying gas laws and performing calculations in chemistry.
8. Gases, Liquids and Solids
Standard Temperature and Pressure
8. Gases, Liquids and Solids
Standard Temperature and Pressure: 동영상 및 연습문제
주제 요약
Standard Temperature and Pressure (STP) is a common set of gas conditions used in calculations. At STP, the temperature is 273.15 K (0°C) and the pressure is 1 atm. These values are often substituted into the ideal gas law, \(PV=nRT\) , or its rearranged form \(n=\frac{PV}{RT}\) to find moles, volume, or related quantities.
A key idea tied to STP is the standard molar volume, the volume of 1 mole of an ideal gas at these conditions. Using \(V=\frac{nRT}{P}\) with \(n=1\) mol, \(T=273.15\) K, and \(P=1\) atm gives 22.4 L. This creates the useful conversion factor 1 mol gas = 22.4 L at STP, which links moles and gas volume directly and supports both gas-law and stoichiometric calculations.
Standard Temperature and Pressure conditions serves as a reference point for scientists to study the properties of gases and compare experimental results.
0
개념
Standard Temperature and Pressure Concept 1
영상 길이:
33sStandard Temperature and Pressure Concept 1 Video Summary
워크시트로 더 똑똑하게 공부하세요.
각 영상을 인쇄 가능한 워크시트로 따라 하세요
0
예시
Standard Temperature and Pressure Example 1
영상 길이:
2mStandard Temperature and Pressure Example 1 Video Summary
To determine the mass of oxygen gas present in a sample with a volume of 325 mL at standard temperature and pressure (STP), we can utilize the ideal gas law. At STP, the pressure is 1 atmosphere, and the temperature is 273.15 Kelvin. The ideal gas law can be expressed as:
\[ n = \frac{PV}{RT} \]
Where:
- n = number of moles
- P = pressure (1 atm)
- V = volume in liters (0.325 L)
- R = ideal gas constant (0.08206 L·atm/(mol·K))
- T = temperature in Kelvin (273.15 K)
First, convert the volume from milliliters to liters:
\[ V = 325 \, \text{mL} = 0.325 \, \text{L} \]
Next, substitute the values into the equation to find the number of moles:
\[ n = \frac{(1 \, \text{atm})(0.325 \, \text{L})}{(0.08206 \, \text{L·atm/(mol·K)})(273.15 \, \text{K})} \]
Calculating this gives:
\[ n \approx 0.01450 \, \text{moles of } O_2 \]
To convert moles to grams, use the molar mass of oxygen gas (O2), which is 32 grams per mole:
\[ \text{mass} = n \times \text{molar mass} \]
\[ \text{mass} = 0.01450 \, \text{moles} \times 32 \, \text{g/mol} \]
This results in:
\[ \text{mass} \approx 0.464 \, \text{grams of } O_2 \]
When considering significant figures, the final answer should reflect three significant figures, resulting in:
\[ \text{mass} \approx 0.464 \, \text{grams of } O_2 \]
In summary, by applying the ideal gas law and converting moles to grams, we find that a sample of oxygen gas with a volume of 325 mL at STP contains approximately 0.464 grams of O2.
0
개념
Standard Temperature and Pressure Concept 2
영상 길이:
1mStandard Temperature and Pressure Concept 2 Video Summary
In the context of standard temperature and pressure (STP), the concept of standard molar volume is crucial for understanding the behavior of gases. Standard molar volume refers to the volume occupied by one mole of an ideal gas at STP, which is defined as a temperature of 273.15 Kelvin and a pressure of 1 atmosphere.
The relationship between volume, moles, and the ideal gas law can be expressed with the formula:
V = n \(\cdot\) \(\frac{RT}{P}\)
In this equation, V represents volume, n is the number of moles, R is the ideal gas constant, T is the temperature in Kelvin, and P is the pressure in atmospheres. When we consider 1 mole of an ideal gas at STP, the moles cancel out, and we can simplify the equation to find the volume:
V = \(\frac{RT}{P}\)
Substituting the values for R (0.0821 L·atm/(K·mol)), T (273.15 K), and P (1 atm), we find that the volume is:
V = 0.0821 \(\cdot\) 273.15 / 1 = 22.4 \(\text{ liters}\)
This result indicates that the standard molar volume of an ideal gas at STP is 22.4 liters. This value serves as a vital conversion factor, allowing for the conversion between moles and volume for any ideal gas under these conditions. Therefore, whenever dealing with 1 mole of an ideal gas at STP, one can confidently use the standard molar volume of 22.4 liters.
0
예시
Standard Temperature and Pressure Example 2
영상 길이:
1mStandard Temperature and Pressure Example 2 Video Summary
To determine the number of moles of chlorine gas (Cl2) occupying a volume of 15.7 liters at standard temperature and pressure (STP), we can utilize two different methods based on the principles of gas laws.
The first method involves using the standard molar volume of an ideal gas, which is 22.4 liters per mole at STP. By applying this conversion factor, we can calculate the moles of Cl2 as follows:
Given:
Volume (V) = 15.7 liters
Conversion factor = 1 mole / 22.4 liters
Calculating moles:
moles = 15.7 liters × (1 mole / 22.4 liters) = 0.701 moles of Cl2
The second method employs the ideal gas law, represented by the equation:
PV = nRT
Where:
- P = pressure (1 atmosphere at STP)
- V = volume (15.7 liters)
- n = number of moles
- R = ideal gas constant (0.0821 L·atm/(K·mol))
- T = temperature (273.15 K at STP)
Rearranging the equation to solve for n gives:
n = PV / RT
Substituting the known values:
n = (1 atm) × (15.7 L) / (0.0821 L·atm/(K·mol) × 273.15 K)
Calculating this yields:
n ≈ 0.701 moles of Cl2
Both methods yield the same result, demonstrating that we can determine the number of moles of a gas at STP either through the standard molar volume or by applying the ideal gas law. Understanding these approaches is essential for solving gas-related problems in chemistry.
0
문제
A sample of dichloromethane gas (CH2Cl2) occupies 32.6 L at 310 K and 5.30 atm. Determine its volume at STP?
A
145 L
B
150 L
C
320 L
D
350 L
E
390 L
0
문제
Which gas sample has the greatest volume at STP?
A
10.0 g He
B
10.0 g Ne
C
10.0 g N2
D
All have the same volume
0
문제
Nitrogen and hydrogen combine to form ammonia via the following reaction:
1 N2 (s) + 3 H2 (g) → 2 NH3 (g)
What mass of nitrogen is required to completely react with 800.0 mL H2 at STP?
A
0.3330 g
B
0.5121 g
C
0.8025 g
D
1.018 g
E
1.369 g
더 연습하고 싶어?
더 많은 세트
플래시카드로 이 주제의 정의를 복습해 보세요
더 많은 세트학생들이 이 주제에 대해 묻는 질문은 다음과 같습니다:
Standard Temperature and Pressure (STP) is a set of reference conditions commonly used in gas calculations. At STP, the temperature is defined as 0 degrees Celsius or 273.15 Kelvin, and the pressure is 1 atmosphere (atm). These fixed conditions allow chemists to standardize measurements and calculations involving gases, making it easier to compare results and apply the ideal gas law. Using STP simplifies the relationship between gas volume, pressure, temperature, and moles, especially when dealing with ideal gases.
The standard molar volume is the volume occupied by one mole of an ideal gas at STP. It is calculated using the ideal gas law, . At STP, pressure is 1 atm, temperature is 273.15 K, and the number of moles is 1 mole. The gas constant is 0.0821 L·atm/(mol·K). Plugging these values into the equation and solving for volume gives approximately 22.4 liters. This means 1 mole of an ideal gas occupies 22.4 L at STP.
The Kelvin scale is used in gas law calculations because it is an absolute temperature scale starting at absolute zero, where molecular motion theoretically stops. Unlike Celsius, Kelvin temperatures are always positive, which is essential for gas law equations like because temperature must be in absolute units to avoid mathematical errors such as division by zero or negative volumes. At STP, the temperature is 273.15 K, which corresponds to 0°C, ensuring consistent and accurate calculations.
The standard molar volume of 22.4 liters at STP provides a direct conversion factor between moles and volume for an ideal gas. Since 1 mole of gas occupies 22.4 L at STP, you can convert moles to volume by multiplying the number of moles by 22.4 L/mol. Conversely, to find moles from a given volume at STP, divide the volume by 22.4 L/mol. This relationship simplifies calculations and helps quickly estimate the amount of gas present or the volume it occupies under standard conditions.
Using 1 atmosphere (atm) as the standard pressure in STP provides a consistent reference point for gas calculations. One atmosphere is the average atmospheric pressure at sea level, making it a practical and widely accepted standard. This standardization allows chemists to compare gas behavior under the same pressure conditions and apply the ideal gas law reliably. It also simplifies calculations by fixing one variable, so changes in volume or temperature can be studied more easily.
