A geyser heats water flowing at the rate of 3.0 litres per minute from 27 °C to 77 °C. If the geyser operates on a gas burner, what is the rate of consumption of the fuel if its heat of combustion is 4.0 × 104 J/g?
A geyser heats water flowing at the rate of 3.0 litres per minute from 27 °C to 77 °C. If the geyser operates on a gas burner, what is the rate of consumption of the fuel if its heat of combustion is 4.0 × 104 J/g?

Solution:

Given
The water is moving at rate of 3.0 litres per minute.
The geyser heats the water, elevating the temperature from 27 degrees Celsius to 77 degrees Celsius as result.

Initial temperature, T1 = 270 C

Final temperature, T2 = 770 C

Rise in temperature, T = T2 – T1

T= 77 – 27

T= 500 C

Heat of combustion = 4 x 104 J / g

Specific heat of water, C = 4.2 J / g 0C

Mass of flowing water, m = 3.0 litre / min = 3000 g / min

Using Total heat , Q = mcT

Q= 3000 x 4.2 x 50

On evaluating, we get,

Q= 6.3 x 105 J / min

Rate of consumption = 6.3 x 10/ (4 x 104)

On solving we get, = 15.75 g/min

Therefore, rate of consumption is 15.75 g/min