A 3.5 kg iron shovel is left outside through the winter. The shovel, now orange with rust, is rediscovered in the spring. Its ma
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Answer :
Standard enthalpy of formation : It is defined as the enthalpy change for the reaction that forms one mole of compound from its elements. All the substances in their standard states.
The balanced chemical equation for the reaction is,
In the balance reaction, Strontium (Sr), Carbon (C) and Strontium carbonate are in solid state and oxygen is in gaseous state.
Answer:
The time required to melt the frost is 3.25 hours.
Explanation:
The time required to melt the frost dependes on the latent heat of the frost and the amount of heat it is transfered by convection to the air .
The heat transferred per unit area can be expressed as:
being hc the convective heat transfer coefficient (2 Wm^-2K^-1) and ΔT the difference of temperature (20-0=20 °C or K).
If we take 1 m^2 of ice, with 2 mm of thickness, we have this volume
The mass of the frost can be estimated as
Then, the amount of heat needed to melt this surface (1 m²) of frost is
The time needed to melt the frost can be calculated as