30 g of air ( c v = 0.177 cal g − 1 ° C − 1 ) is in a cylinder under a movable piston at a constant 2.0 atm. Its original volume is 9000 c m 3 at 2 0 ∘ C. How much heat in joules must be added to raise it to 30 0 ∘ C? (1 cal = 4.18 J, 1 atm = 1.013 × 1 0 5 Pa, nearest integer)

Δ U = m c v Δ T = 30 × 0.177 × 280 = 1487 cal = 6215 J. W = P Δ V = P V 1 T 1 Δ T = 2 × 1.013 × 1 0 5 × 9 × 1 0 − 3 × 293 280 = 1742 J. Q = 7957 J.

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PhysicsHeat & ThermoThermodynamics Laws & Specific Heats of GasesMedium2 minQB

PhysicsMediuminteger

30 g of air ( $c_{v} = 0.177$ cal $g^{- 1}$ ° $C^{- 1}$ ) is in a cylinder under a movable piston at a constant 2.0 atm. Its original volume is 9000 $c m^{3}$ at $2 0^{\circ}$ C. How much heat in joules must be added to raise it to $30 0^{\circ}$ C? (1 cal = $4.18$ J, 1 atm = $1.013 \times 1 0^{5}$ Pa, nearest integer)

Answer:

7957

Solution:

$Δ U = m c_{v} Δ T = 30 \times 0.177 \times 280 = 1487$ cal = $6215$ J. $W = P Δ V = P V_{1} \frac{Δ T}{T _{1}} = 2 \times 1.013 \times 1 0^{5} \times 9 \times 1 0^{- 3} \times \frac{280}{293} = 1742$ J. $Q = 7957$ J.

Subject:PhysicsTopic:Heat & ThermoSubtopic:Thermodynamics Laws & Specific Heats of Gases

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