69. The student's skin was obviously warmer than the initial temperature of the bracelet. According to the second law of thermodynamics, heat transfers from a higher temperature to a lower temperature hence heat transfers from the student's skin to the bracelet warming up the bracelet.
70. moles of copper=mass of copper/molar mass of copper
=30.1g/(63.55g/mol)= 0.4736 moles Cu
71. Delta H( heat released) = mCp(deltaT) = 30.1g(0.385 J/gK)(33-19)K = 162.23J
72. Copper is chemically less active than iron.
Mass of Li = 237.38 g
<h3>Further explanation</h3>
The mole itself is the number of particles contained in a substance amounting to 6.02.10²³
<h3>Known</h3>
Moles of Li = 34.2
Molar mass(MW) of Li = 6.941 g/mol
then mass of Lithium (Li) :
Explanation:
The above two reactions xcan also be written in form of single chemcial equation:
1. Color of ferric chloride solution is yellow. This is due to presence of ferric ions which have yellow color in their aqueous solutions.
2. KSCN has the colorless solution. This due to potassium ion forms colorless aqueous solution.
3. On mixing, KSCN with we will get blood red color solution of .