Tijuan mixed a solid and a liquid together in a beaker. He determined that a chemical change occurred. ... After a week, he observed that only solid salt remained in the cup and the mass had decreased I hope this helped! In some way
(1) The quantity of heat required to melt 175 g Cu is 35.88 kJ.
(2) The substance that releases 21.2 kJ of energy when 1.42 mol of it freezes is iron.
<h3>
What is heat of fusion?</h3>
Heat of fusion is the energy required to melt 1 mole of a substance.
<h3>What is heat of vaporization?</h3>
The heat energy required to vaporize 1 mole of a substance has been heat of vaporization.
Heat of fusion of copper (Cu) is given as 13 kJ/mol
Number of moles of 175 g of copper = 175/63.5 = 2.76 moles
Q = nΔH
Q = 2.76 mol x 13 kJ/mol = 35.88 kJ
Thus, the quantity of heat required to melt 175 g Cu is 35.88 kJ.
<h3>Heat of fusion of the substance</h3>
ΔH(fus) = Q/n
where;
- n is number of moles
- Q is quantity of heat released
ΔH(fus) = 21.2 kJ / 1.42 mol
ΔH(fus) = 14.93 kJ/mol
From the table the substance with latent heat of fusion of 14.9 kJ/mol is iron.
Thus, the substance that releases 21.2 kJ of energy when 1.42 mol of it freezes is iron.
Learn more heat of fusion here: brainly.com/question/87248
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growing only enough crops for food to fed the family
Explanation:
subsistence farming is the practice of growing crops only for own use .. some developing countries are only doing farming for their personal use so they are in the stage of developing ..in a country like nepal we not being able to trade our farming .if we want to export then also we arenot getting the good market ..