A scuba diver's tank contains .25 kg of oxygen compressed into a volume of 4.3 L (for oxygen, 32g = 1 mole)

Calculate the gas pressure inside the tank at 9 degrees Celsius
What volume would this occupy at 26 degrees Celsius and .95 atmospheres?

can someone tell me how many moles i need and what other formula do i use?

moles O2 = grams/molar mass.

Then PV = nRT, substitute and solve for P for the first part.
Use PV = nRT for the second part and solve for P.
I would use PV = nRT for the third part.

To calculate the gas pressure inside the tank, you can use the ideal gas law equation:

PV = nRT

where:
P = pressure
V = volume
n = number of moles
R = ideal gas constant
T = temperature (in Kelvin)

To find the number of moles of oxygen in the tank, you need to divide its mass by the molar mass of oxygen.

Given:
Mass of oxygen = 0.25 kg
Molar mass of oxygen = 32 g/mol

First, we need to convert the mass of oxygen from kg to g:
0.25 kg = 250 g

Next, we can calculate the number of moles of oxygen:
Number of moles (n) = Mass / Molar mass
n = 250 g / 32 g/mol = 7.8125 mol

Now, we have the number of moles of oxygen.

To calculate the gas pressure at 9 degrees Celsius, we need to convert the temperature to Kelvin. Use the formula:
T(K) = T(°C) + 273.15

Given:
Temperature (T) = 9 °C

Convert temperature to Kelvin:
T(K) = 9 + 273.15 = 282.15 K

Now, we can substitute the values into the ideal gas law equation:
PV = nRT

P * 4.3 L = 7.8125 mol * R * 282.15 K

To find the gas pressure (P), we need to know the value of the ideal gas constant (R), which is 0.0821 L·atm/(mol·K).

P * 4.3 L = 7.8125 mol * 0.0821 L·atm/(mol·K) * 282.15 K

Simplifying the equation, we can solve for P:
P = (7.8125 mol * 0.0821 L·atm/(mol·K) * 282.15 K) / 4.3 L

Calculating the equation will give you the gas pressure inside the tank at 9 degrees Celsius.

To find the volume of the gas at 26 degrees Celsius and 0.95 atmospheres, we can use the ideal gas law equation:

PV = nRT

Given:
Temperature (T) = 26 °C
Pressure (P) = 0.95 atm

First, we need to convert the temperature to Kelvin:
T(K) = 26 + 273.15 = 299.15 K

Now, we can substitute the values into the ideal gas law equation:
P1 * V1 = n * R * T1

Using the subscript "1" to represent the initial conditions inside the tank.

To find the volume at the new conditions, we need to rearrange the equation:
V2 = (n * R * T2) / P2

V2 = (7.8125 mol * 0.0821 L·atm/(mol·K) * 299.15 K) / 0.95 atm

Calculating the equation will give you the volume of the gas at 26 degrees Celsius and 0.95 atmospheres.