a 16 gram sample of oxygen has a volume of 11.2L at standard pressure . what is the temp of the oxygen ?

Use PV = nRT

n = grams/molar mass O2
Solve for T (in kelvin)

so when i get my answer

i add 273 to it?

Maybe yes, maybe no, but definitely you don't add 273.

If you want T in kelvin that is your answer. If you want it in degrees C, you subtract 273 from the calculation.
K = 273 + C

To find the temperature of the oxygen, we can use the ideal gas law equation:

PV = nRT

Where:
P = pressure (in atm)
V = volume (in liters)
n = number of moles
R = ideal gas constant (0.0821 L·atm/(mol·K))
T = temperature (in Kelvin)

First, we need to convert the given mass of oxygen into moles. To do this, we'll use the molar mass of oxygen, which is 32 g/mol.

Given mass of oxygen = 16 grams
Molar mass of oxygen = 32 g/mol

Number of moles of oxygen = (Given mass of oxygen) / (Molar mass of oxygen)
Number of moles of oxygen = 16 g / 32 g/mol
Number of moles of oxygen = 0.5 mol

Now, let's rearrange the ideal gas law equation to solve for temperature:

T = (PV) / (nR)

Substituting the given values into the equation:
P = standard pressure = 1 atm
V = volume = 11.2 L
n = number of moles = 0.5 mol
R = ideal gas constant = 0.0821 L·atm/(mol·K)

T = (1 atm * 11.2 L) / (0.5 mol * 0.0821 L·atm/(mol·K))

Simplifying the equation:
T = 22.4 / 0.04105
T ≈ 545.3 K

Therefore, the temperature of the oxygen is approximately 545.3 Kelvin.