When a solid turns into a liquid
Example: Ice cube melts into water
Answer:
20.79 kilojoules
Explanation:
Using Q = m×c×∆T
Where;
Q = Quantity of heat (J)
c = specific heat capacity of solid DMSO (1.80 J/g°C)
m = mass of DMSO
∆T = change in temperature
According to the provided information, m= 50g, initial temperature = 19.0°C, final temperature= 250.0°C
Q = m×c×∆T
Q = 50 × 1.80 × (250°C - 19°C)
Q = 90 × 231
Q = 20790 Joules
To convert Joules to kilojoules, we divide by 1000 i.e.
20790/1000
= 20.79 kilojoules
Hence, 20.79 kilojoules of energy is required to convert 50.0 grams of solid DMSO to gas.
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Answer:
(a) 282 kJ
(b) 67.4 Calories
Explanation:
(a) The molar enthalpy, ΔH = −2802.5 kJ/mol, means that the heat produced by the reaction is 2802.5 kJ per mol of glucose.
We can multiply the enthalpy by the number of moles of glucose to get the heat produced by the metabolism. Grams of glucose will be converted to moles using the molar mass of glucose (180.156 g/mol):
(18.1 g)(mol/180.156g)(2802.5 kJ/mol) = 282 kJ
(b) Using the result we obtained above, kJ will be converted to Calories using the conversion factor of 4.184J = 1 cal. Calorie with a capital C is the same as a kilocalorie.
(282 kJ)(1 cal/4.184J) = 67.4 kcal = 67.4 Calories
