Question

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 Jg^-1?

Answer 1

Volume of water heated = 3.0 litre per minute

mass of water heated, m = 3000 g per minute

increase in temperature, ∆T = 77°C – 27°C = 50°C

specific heat of water, c= 4.2Jg^-1 °C^-1

amount of heat used, Q = mc ∆T

or Q = 3000 g min^-1 × 4.2Jg^-1

^°C^-1 × 50°C

= 63 × 10⁴J min^-1

rate of combustion of fuel = \(\frac{63×10^4Jmin^-1}{4.0×10^4Jg^−1}\)

= 15.75gmin^-1.