Q1) In an espresso coffee machine, steam at 100°C is passed into milk to heat it

Question

Q1) In an espresso coffee machine, steam at 100°C is passed into milk to heat it.
Calculate
(a) the energy needed to heat 175 g of milk from room temperature (20°C) to 80°C,
(b) the mass of steam condensed by heating the milk,
(c) the mass of liquid water at its boiling point needed to mix with 175 g of milk to give the same temperature change of 20°C to 80°C.
(specific heat capacity of milk = 4.0 kJ kg-1 K-1,
specific heat capacity of water = 4.2 kJ kg-1 K-1,
specific latent heat of steam = 2.2 MJ kg-1)

Explanation / Answer

a) 175*10-3*4*103*(80-20)

=42000 J

b) m=42000/2.2*106

=.01909 kg

c)m=42000/(4.2*103*60)

=.167 kg

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