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.
Answer:
A. They are nonreactive gases
Answer:
Work is the use of force to move an object. It is directly related to both the force applied to the object and the distance the object moves. Work can be calculated with this equation: Work = Force x Distance.
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The atomic number represents the number of protons present in an atom.Therefore,the answer is B.
Atoms are the unit of the molecule of the compound. The 3.01 x 10²⁴ atoms of oxygen are present in 5 moles of water and 3 moles of carbon dioxide in the sample.
<h3>What are atoms?</h3>
Atoms are the smallest fundamental unit of the compounds that can be given by Avogadro's number.
For calculating the oxygen atoms in 5 mole water:
If 1 mole = 6.02 × 10²³
Then, 5 moles = 5 × 6.02 × 10²³
Hence, 3.01 x 10²⁴ atoms of oxygen are present in 5 moles of water.
Moles of carbon dioxide in the sample is calculated as:
If 1 mole of carbon dioxide = 6.02 × 10²³ molecules
Then moles in 1.8 x 10²⁴ molecules will be,
(1.8 x 10²⁴ molecules) ÷ (6.02 × 10²³ molecules) = 3 moles
Hence, 3 moles of carbon dioxide is present in the sample.
Learn more about Avogadro's number here:
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