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.
The answer is 2 pairs. The carbon atom has 4 electrons and oxygen atom has 6 electrons. The purpose of shared electron is to get 8 electrons at the outer layer. So the carbon atom needs to share 4 electrons which is 2 pairs with oxygen to be stable.
The answer is the climate of a place. The troposphere is the lowermost level of Earth's air, and is likewise where closely all weather and climate situations happen. It covers about 75% of the air's mass and 99% of the total form of water vapor and aerosols.
Answer:
When mixing a base with a liquid, an acid-based reaction.
Explanation:
When an acid and a base are placed together, they react to neutralize the acid and base properties, producing a salt. The H(+) cation of the acid combines with the OH(-) anion of the base to form water.
