Question

A 32.5-g glass thermometer reads 24.1 ∘C before it is placed in 115 mL of water. When the water and thermometer come to equilibrium, the thermometer reads 41.8 ∘C. Ignore the mass of fluid inside the glass thermometer. The value of specific heat for water is 4186 J/kg⋅C∘, and for glass is 840 J/kg⋅C∘.	Part A What was the original temperature of the water? Express your answer using three significant figures. T T = nothing   ∘C   SubmitRequest Answer Provide Feedback Next

Answer 1

Let everything is insulated and there is no heat loss.

Energy gained by the thermometer (E1) must be equal to the energy lost by the water (E2).

specific heat of water is 4186 J/kgC
specific heat glass 840 J/kgK
density of fresh water at 24.1C = 0.100 g/cm³ (approx)
115 mL = 115 cm³
115 cm³ x 0.100 g/cm³ = 115 g = 0.115 kg

You really need to know the exact type of glass, as they vary.

E1 = 840 J/kgK x 0.0325 kg x (41.8–24.1)
E2 = 4186 J/kgC x 0.115 kg x (T–41.8)

840 x 0.0325 x (41.8–24.1) = 4186 x 0.115 x (T–41.8)
solve for T=42.80 C