1. Ideal Gas Law:

The ideal gas law relates pressure (P), volume (V), number of moles (n), the ideal gas constant (R), and temperature (T):

PV = nRT

2. STP Conditions:

STP (Standard Temperature and Pressure) is defined as:

* Temperature (T) = 0°C = 273.15 K

* Pressure (P) = 1 atm

3. Ideal Gas Constant:

The ideal gas constant (R) is 0.0821 L·atm/mol·K.

4. Calculation:

* We know V = 6 L

* We know P = 1 atm

* We know T = 273.15 K

* We know R = 0.0821 L·atm/mol·K

Now we can solve for n (moles):

n = (PV) / (RT) = (1 atm * 6 L) / (0.0821 L·atm/mol·K * 273.15 K) ≈ 0.268 mol

Therefore, there are approximately 0.268 moles of Helium in 6 liters at STP.