Students are asked to determine the specific heat capacity of an ionic solid that is…
PHYSICS · Multi-part · A Level · Physics · Measurements and their errors · Measurements and their errors
Problem
Students are asked to determine the specific heat capacity of an ionic solid that is a potential phase-change material for thermal energy storage. They heat a 30.00 g sample of the solid to 160.0 °C and then transfer it to a simple calorimeter containing 150.0 g of water at 25.00 °C. The calorimeter has a measured heat capacity of 12.0 J °C⁻¹. The final equilibrium temperature is 28.90 °C. All measured quantities and their associated expanded uncertainties (at the 95 % confidence level) are given in the table below.
Quantity | Value | Uncertainty
Mass of solid | 30.00 g | ±0.05 g
Initial temp.
of solid | 160.0 °C | ±0.2 °C
Mass of water | 150.0 g | ±0.05 g
Initial temp.
of water | 25.00 °C | ±0.05 °C
Heat capacity
of calorimeter | 12.0 J °C⁻¹ | ±0.4 J °C⁻¹
Final temp. | 28.90 °C | ±0.05 °C
(a) Calculate the specific heat capacity of the ionic solid based on the data provided.
(b) Using appropriate propagation of uncertainty methods for products and differences, determine the absolute uncertainty in the calculated specific heat capacity. Report your final answer with the correct number of significant figures and its uncertainty.
(c) Discuss two experimental assumptions made in this calorimetric determination and explain how violation of each assumption would affect the magnitude of the calculated specific heat capacity.