A helium balloon is inflated to a volume of 5.65 L and a pressure of 10.2 atm at a temperature of 25 °C - VCE - SSCE Chemistry - Question 16 - 2012 - Paper 1

The Ideal Gas Law is given by: $PV = nRT$ where:

• P = pressure in atm = 10.2 atm
• V = volume in L = 5.65 L
• n = number of moles of gas
• R = ideal gas constant = 0.0821 L·atm/(K·mol)
• T = temperature in Kelvin = 298.15 K

Rearranging the formula gives: $n = \frac{PV}{RT}$

Substituting the known values into the equation: $n = \frac{(10.2 \text{ atm})(5.65 \text{ L})}{(0.0821 \text{ L·atm/(K·mol)})(298.15 \text{ K})}$

Calculating it step-by-step:

1. Calculate the numerator:
   • $10.2 \times 5.65 = 57.63$
2. Calculate the denominator:
   • $0.0821 \times 298.15 \approx 24.475$
3. Finally, the number of moles n is: $n = \frac{57.63}{24.475} \approx 2.35$ This value rounds to 2.36 moles, which corresponds to option C.