To calculate the pressure of the helium gas in the tank, we can use the ideal gas law equation:
PV = nRT
where P is the pressure of the gas, V is the volume of the tank, n is the number of moles of the gas, R is the ideal gas constant, and T is the temperature of the gas in Kelvin.
First, we need to convert the temperature from Celsius to Kelvin by adding 273.15 to it:
T = 25°C + 273.15 = 298.15 K
Next, we need to calculate the number of moles of helium gas in the tank using its mass and molar mass:
n = m/M
where m is the mass of the gas and M is its molar mass. The molar mass of helium is approximately 4.00 g/mol.
n = 2.0 g / 4.00 g/mol = 0.50 mol
Now we can substitute the values we have into the ideal gas law equation and solve for P:
P = nRT/V
P = (0.50 mol)(0.08206 L·atm/(mol·K))(298.15 K)/(5.0 L)
P = 2.43 atm
Therefore, the pressure of the helium gas in the tank is approximately 2.43 atm.