Question

100 W heater is switched on for 5 minutes to melt ice. What is the mass of ice that melts at 0C. Specific latent heat of fusion of ice is 334 J/g.

Answer 1

Answer:

You'll need 10 g.

Latent heat of fusion is the energy needed to melt a certain amount of substance.

In your case you need 334 J of energy to melt 1 g of ice. If you can supply 3.34 kJ of energy you have:

#Q=mL_f# where:

#Q# is the heat you can supply, in this case 3.34 kJ;

#m# is the mass of the substance, our unknown;

#L_f# is the latent heat of fusion of water, 334 J/g.

Rearranging you have:

#m=(Q/L_f)=(3.34*10^3)/334=10g#

Remember

Latent Heat is the energy your substance needs to change its phase (solid -> liquid) and is not used to increase its temperature but to change the "connections" between the particles of the substance making it change from a solid (rigid connections) to a liquid (loose connections).

Answer 2

Given: 100 W heater is switched on for 5 minutes to melt ice. Specific latent heat of fusion of ice is 334 J/g.

To find: Mass of ice that melts at 0° C

Explanation: Power of heater = 100 W

Time= 5 minutes

= 5*60 ( 1 minute= 60 seconds)

= 300 seconds

Total heat given= Power * Time

= 100 * 300 J

= 3000 J

The heat given by the heater is used to melt the ice at 0°C.

Specific latent heat of fusion= 334 J/g

Mass of ice melted

= Total heat given/ Latent heat of fusion

= 3000 J / 334 J/g

= 8.98 g

Therefore, the mass of ice that melts at 0° C is 8.98 grams.