A portion of substance X is warmed through two separate intervals: • Interval 1: from…
PHYSICS · Single correct · A Level · Physics · Further mechanics and thermal physics · Further mechanics and thermal physics
Problem
A 100g portion of substance X is warmed through two separate 10∘C intervals:
• Interval 1: from 10∘C to 20∘C while X is a solid (specific heat 0.90Jg−1∘C−1).
• Interval 2: from 30∘C to 40∘C after X has melted and is a liquid (specific heat 2.1Jg−1∘C−1).
Which of the following best explains why more heat is required during Interval 2 than during Interval 1?
(a) Because the Kelvin temperature scale is higher in Interval 2, each degree represents more energy, so more heat is required.
(b) The liquid has a larger specific heat capacity, so each degree of warming requires more energy per gram.
(c) Heat is lost to the surroundings more rapidly at the higher temperatures reached in Interval 2, so additional heat must be supplied.
(d) Energy absorbed during melting remains stored as latent heat that must first be overcome before the liquid’s temperature can rise further.