Using molar volume (STP) or the ideal gas law equation, determine the molar mass, g/mole, of each of the following:1.)11.1g of a gas that has a volume of 1.50L at STP. 2.) 0.742g of a gas that has a volume 860mL at 1.28atm and 18∘C. 3.) 2.42g of a gas that has a volume 1.88L at 695mmHg and 19∘C.
1)
Use PV = nRT and solve for n = number of mols of the gas. Then n = grams/molar mass gas. You know grams and n, solve for molar mass.
I think the others are done the same way.
Read my response again. I told you how.
You use PV = nRT and solve for n = number of mols. Then n = grams/molar mass. You have n from the PV = nRT and you have grams from the problem. Substitute those and solve for molar mass of the gas. You're making it harder than it is. Don't get intimidated by chemistry.
How are we suppose to solve for the molar mass because we don't have the chemical formula for the gas?
To determine the molar mass of a gas using the molar volume (STP) or the ideal gas law equation, you first need to convert the given information into the appropriate units. Here's how you can approach each question:
1) 11.1g of a gas that has a volume of 1.50L at STP:
- STP stands for Standard Temperature and Pressure, which is defined as 0°C (or 273.15 K) and 1 atmosphere (atm) of pressure.
- First, convert the given volume of the gas to liters (L), if necessary. In this case, no conversion is necessary since the volume is already given as 1.50L.
- Next, use the ideal gas law equation: PV = nRT. At STP, the pressure (P) is 1 atm, and the temperature (T) is 0°C or 273.15 K.
- Rearrange the equation to solve for the number of moles (n): n = PV / RT.
- Substituting the known values, we have n = (1 atm * 1.50 L) / (0.0821 atm·L/mol·K * 273.15 K).
- Calculate the value of n, which represents the number of moles of the gas.
- Finally, to find the molar mass, divide the given mass (11.1g) by the number of moles (n) calculated in the previous step.
2) 0.742g of a gas that has a volume of 860mL at 1.28atm and 18°C:
- First, convert the given volume of the gas to liters (L), if necessary. In this case, divide 860 mL by 1000 to get 0.860 L.
- Next, convert the temperature from Celsius to Kelvin (K) by adding 273.15: 18°C + 273.15 = 291.15 K.
- Use the ideal gas law equation: PV = nRT. In this case, pressure (P) is given as 1.28 atm, volume (V) is 0.860 L, and temperature (T) is 291.15 K.
- Rearrange the equation to solve for the number of moles (n): n = PV / RT.
- Substituting the known values, we have n = (1.28 atm * 0.860 L) / (0.0821 atm·L/mol·K * 291.15 K).
- Calculate the value of n, which represents the number of moles of the gas.
- Finally, to find the molar mass, divide the given mass (0.742g) by the number of moles (n) calculated in the previous step.
3) 2.42g of a gas that has a volume of 1.88L at 695mmHg and 19°C:
- First, convert the given volume of the gas to liters (L), if necessary. In this case, the volume is already given as 1.88L.
- Convert the pressure from mmHg to atm by dividing by 760: 695 mmHg / 760 mmHg/atm = 0.9145 atm.
- Convert the temperature from Celsius to Kelvin (K) by adding 273.15: 19°C + 273.15 = 292.15 K.
- Use the ideal gas law equation: PV = nRT. In this case, pressure (P) is 0.9145 atm, volume (V) is 1.88 L, and temperature (T) is 292.15 K.
- Rearrange the equation to solve for the number of moles (n): n = PV / RT.
- Substituting the known values, we have n = (0.9145 atm * 1.88 L) / (0.0821 atm·L/mol·K * 292.15 K).
- Calculate the value of n, which represents the number of moles of the gas.
- Finally, to find the molar mass, divide the given mass (2.42g) by the number of moles (n) calculated in the previous step.
By following these steps, you can determine the molar mass (g/mol) of each of the given gases using either the molar volume (STP) or the ideal gas law equation.