How many Joules of heat are required to melt 250 grams of ice at 0°C? AHfus = 334 J/g
AHvap = 2258 J/g
Cp= 4.184 J/g C

Heat required : Q = 83500 J = 83.5 kJ

Given

mass ice = 250 g at 0°C

Required

The heat required

Solution

The heat to change the phase can be formulated :

Q = m.Lf (melting/freezing)

Lf=latent heat of fusion

Input the value :

Q = 250 g x 334 J/g

Q = 83500 J

the equation that correctly represent the reaction for formation of ammonia is

n2+ 3h2 → 2nh3 (answer d)

1 mole of nitrogen gas (n2) react with 3 moles of hydrogen gas (h2) to form 2 moles of ammonia ( nh3). this is in a process known as haber process were iron is used as a catalyst and reaction take place that a higher temperature and pressure. the process is exothermic hence energy is released.

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