Calculate the pressure of a helium sample at -207.3°C and 768 mL if it exerts a pressure of 175 kPa at 25.0°C and 925 mL

Question

Calculate the pressure of a helium sample at -207.3°C and 768 mL if it exerts a pressure of 175 kPa at 25.0°C and 925 mL

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Answer 1

From the ideal gas law, P₂V₂ / P₁V₁ = nRT₂ /nRT₁ which yields P₂ = T₂P₁V₁ / T₁V₂ when the number of moles is the same. P₂ = (-207.3 +273.15 K) (175 kPa) (925 mL) / [(25.0 + 273.15 K) (768 mL)] = 46.6 kPa.