- The molar mass of 0.458-gram sample of gas having a volume of 1.20 l at 287 k and 0.980 atm is 9.15g/mol.
- If this sample was placed under extreme pressure, the volume of the sample will decrease.
<h3>How to calculate molar mass?</h3>
The molar mass of a substance can be calculated by first calculating the number of moles using ideal gas law equation:
PV = nRT
Where;
- P = pressure
- V = volume
- T = temperature
- R = gas law constant
- n = no of moles
0.98 × 1.2 = n × 0.0821 × 287
1.18 = 23.56n
n = 1.18/23.56
n = 0.05moles
mole = mass/molar mass
0.05 = 0.458/mm
molar mass = 0.458/0.05
molar mass = 9.15g/mol
- Therefore, the molar mass of 0.458-gram sample of gas having a volume of 1.20 l at 287 k and 0.980 atm is 9.15g/mol
- If this sample was placed under extreme pressure, the volume of the sample will decrease.
Learn more about gas law at: brainly.com/question/12667831
Answer is (b) , because a chemical change happened
The full question asks to decide whether the gas was a specific gas. That part is missing in your question. You need to decide whether the gas in the flask is pure helium.
To decide it you can find the molar mass of the gas in the flask, using the ideal gas equation pV = nRT, and then compare with the molar mass of the He.
From pV = nRT you can find n, after that using the mass of gass in the flask you use MM = mass/moles.
1) From pV = nRT, n = pV / RT
Data:
V = 118 ml = 0.118 liter
R = 0.082 atm*liter/mol*K
p = 768 torr * 1 atm / 760 torr = 1.0105 atm
T = 35 + 273.15 = 308.15 K
n = 1.015 atm * 0.118 liter / [ 0.082 atm*liter/K*mol * 308.15K] =0.00472 mol
mass of gas = mass of the fask with the gas - mass of the flasl evacuated = 97.171 g - 97.129 g = 0.042
=> MM = mass/n = 0.042 / 0.00472 = 8.90 g/mol
Now from a periodic table or a table you get that the molar mass of He is 4g/mol
So the numbers say that this gas is not pure helium , because its molar mass is more than double of the molar mass of helium gas.
Answer:
6.67 mg/kg per dose ( 26.67 mg/kg per day)
Explanation:
400 mg / 60 kg = 6 2/3 mg/kg per dose
per <em>DAY</em> is four times this number
