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Naya [18.7K]
3 years ago
13

Calculate the amount of energy when water at 72 degrees c freezes completely at 0 degrees c

Chemistry
1 answer:
gtnhenbr [62]3 years ago
3 0

<u>Answer:</u>

<em>The amount of energy needed when water at 72 degrees c freezes completely at 0 degrees c is 6.37\times10^4 Joules</em>

<em></em>

<u>Explanation:</u>

Q = m \times c \times \Delta T

where

\Delta T = Final T - Initial T

$Q_{1}=100 g \times 4.184 \frac{J}{g^{\circ} \mathrm{C}} \times\left(72^{\circ} \mathrm{C}-0^{\circ} \mathrm{C}\right)$

Q_1 =30125J

Q is the heat energy in Joules  

c is the specific heat capacity (for water 1.0  cal/(g℃))  or 4.184  J/(g℃)

m is the mass of water

mass of water is assumed as 100 g (since not mentioned)

Q_2  is the heat energy required for the phase change

Q_2 =mass × heat of fusion

\\$Q_{2}=100 g \times 336 \frac{J}{g}$\\\\$Q_{2}=33600 J$

Total heat = Q_1 + Q_2

Total Heat = 30123J + 33600J

= 63725 J

= 6.37\times10^4 Joules is the answer

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