Physics

Calorimetry Issues


Heat

(1) To melt a bar of material w of 1kg it is necessary to heat it to the temperature of 1000 ° C. Being the ambient temperature at the moment analyzed 20 ° C and the specific heat of w = 4.3J /kg. ° C, how much heat does it need to melt the bar?

(2) A 10cm³ iron block is cooled from 300 ° C to 0 ° C. How many calories does the block lose to the environment?

Data: iron density = 7.85g / cm³ and specific heat of iron = 0.11cal / g. ° C

The first step is to find out the mass of the block, knowing its density and volume (it is important to pay close attention to the units of each quantity).

Knowing the mass, we can calculate the amount of body heat:

As Q <0, heat transfer happens in the block direction to the environment (releases heat).

(3) How much heat is absorbed so that 1L frozen water at -20 ° C will vaporize and reach a temperature of 130 ° C.

Dice:

Latent Water Melting Heat: L = 80cal / g

Latent heat of water vaporization: L = 540cal / g

Specific ice heat: c = 0,5cal / g ° C

Specific water heat: c = 1cal / g. ° C

Specific heat of water: c = 0,48cal / g ° C

Water density: d: 1g / cm³

1L = 1dm³ = 1000cm³

m = d.V

m = 1000g

Heat exchanges

(1) A block of unknown material with a mass of 1kg is at a temperature of 80 ° C when touched against another block of the same material, of a mass of 500g and at room temperature (20 ° C). What temperature do the two reach in contact? Assume the blocks are on a calorimeter.

(2) In a kitchen, a kettle with 1L of water boils. To stop it, 500mL of water is added at 10 ° C. What is the system equilibrium temperature?

Any amount of boiling water is at 100 ° C, if the temperature is higher then there will be no liquid water, only steam.