The pressure of the helium gas in the tank is 0.990 atm (at 25°C and with a volume of 5.0 L).
To solve this problem, we can use the ideal gas law:
PV = nRT
where P is the pressure of the gas, V is the volume of the tank, n is the number of moles of gas, R is the ideal gas constant, and T is the temperature of the gas in Kelvin.
First, we need to convert the given temperature of 25 degrees Celsius to Kelvin:
T = 25°C + 273.15 = 298.15 K
Next, we need to calculate the number of moles of helium gas using its mass and molar mass:
n = m/MW
where m is the mass of helium and MW is the molar mass of helium, which is 4.003 g/mol.
n = 2.0 g / 4.003 g/mol = 0.499 moles
Now we can put in the values we have into the ideal gas law and solve for P:
P = nRT/V
P = (0.499 mol)(0.08206 L·atm/mol·K)(298.15 K) / 5.0 L
P = 0.990 atm
Therefore, the pressure of the helium gas in the tank is 0.990 atm (at 25°C and with a volume of 5.0 L).
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The heat of vaporization for ethanol is 0.826 kJ/g
. Calculate the heat energy in joules required to boil 75.25 g
of ethanol.
Answer:
87469.73J
Explanation:
72.25g/0.826kJ/g=87.4697337kJ
Calculate the change in heat when 16.00 g of water vapor (steam) at 100.0°C condenses to liquid water and then cools to 25.50 °C.
The change in heat when 16.00 g of water vapor (steam) at 100.0°C condenses to liquid water and then cools to 25.50°C is -31.25 kJ (exothermic process).
To calculate the change in heat when 16.00 g of water vapor (steam) at 100.0°C condenses to liquid water and then cools to 25.50 °C, we need to consider two separate processes and add their heat changes together:
The heat change during the condensation of steam to liquid water:
The heat change during this process can be calculated using the heat of vaporization of water, which is 40.7 kJ/mol at 100.0°C.
First, we need to determine the number of moles of water in 16.00 g:
moles of water = mass of water / molar mass of water
moles of water = 16.00 g / 18.015 g/mol
moles of water = 0.8886 mol
The heat change during the condensation of steam to liquid water can be calculated as follows:
q1 = moles of water x heat of vaporization
q1 = 0.8886 mol x 40.7 kJ/mol
q1 = 36.21 kJ
The heat change during the cooling of liquid water from 100.0°C to 25.50°C:
The heat change during this process can be calculated using the specific heat capacity of water, which is 4.184 J/g°C.
The temperature change during this process is:
ΔT = final temperature - initial temperature
ΔT = 25.50°C - 100.0°C
ΔT = -74.50°C
The heat change during the cooling of liquid water can be calculated as follows:
q2 = mass of water x specific heat capacity x ΔT
q2 = 16.00 g x 4.184 J/g°C x (-74.50°C)
q2 = -4,958 J
Therefore, the total heat change for the two processes is:
ΔH = q1 + q2
ΔH = 36.21 kJ + (-4,958 J)
ΔH = 36.21 kJ - 4.958 kJ
ΔH = 31.25 kJ
Therefore, the change in heat when 16.00 g of water vapor (steam) at 100.0°C condenses to liquid water and then cools to 25.50°C is -31.25 kJ (exothermic process).
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A sample of gas at a constant
volume initially has a
temperature of 315.0 K with a
pressure of 2.50 atm. The
pressure changes to 3.61 atm.
Calculate the final temperature.
The final temperature of the gas, when the pressure changes from 2.50 atm to 3.61 atm at constant volume, is approximately 454.9 K.
What is the final temperature of the gas?Gay-Lussac's law states that the pressure exerted by a given quantity of gas varies directly with the absolute temperature of the gas.
It is expressed as;
P₁/T₁ = P₂/T₂
Given that:
Initial pressure P₁ = 2.50 atmInitial temperature T₁ = 315.0 KFinal pressure P₂ = 3.61 atmInitial temperature T₂ = ?Plug the given values into the equarion above.
P₁/T₁ = P₂/T₂
P₁T₂ = P₂T₁
[tex]T_2 = \frac{P_2T_1}{P_1}\\ \\T_2 = \frac{3.61 \ *\ 315.0}{2.50} \\\\T_2 = 454.9K[/tex]
Therefore, the final temperature is 454.9 K.
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how would you confirm the presence of lead in an ore?
There are numerous ways to determine whether lead is present in an ore. Atomic absorption spectroscopy is a popular approach. With this method, an ore sample is dissolved in acid and then atomized in a flame or plasma.
The sample's atoms will absorb light at particular wavelengths that are peculiar to the element under investigation. The amount of light absorbed can be used to calculate how much lead is present in the sample. Inductively coupled plasma mass spectrometry and X-ray fluorescence spectroscopy are further techniques. It is crucial to remember that these procedures call for specialized tools and training, thus they ought to only be carried out in a lab by qualified experts.
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