Physical change
iron nail have high melting point, thus, when it is heated, it will not melt very easily.
chemical change
iron nail can rust due to the exposure to the air(oxygen). iron in the nail and oxygen in the air will react together to form iron oxide(rust).
furthermore, the reaction is irreversible.
Heat from deep within Earth is thought to keep the asthenosphere malleable, lubricating the undersides of Earth's tectonic plates and allowing them to move.
Answer:
40.34 g
Explanation:
First, we divide the heat to release by the heat of combustion to obtain the required moles of compound:
541.20 kJ/(1160.00 kJ/mol) = 0.4665 mol
So, we have to burn approximately 0.47 mol of the compound. We convert the moles to mass in grams by using the molar mass:
mass = molar mass x moles = 86.47 g/mol x 0.4665 mol = 40.34 g
Therefore, you must burn 40.34 grams of the compound to release 541.20 kJ of heat.
We need to find the number of moles that each of the given substances. The molar mass of magnesium is 24.3 g/mol and Bromine has a molar mass of 79.90 g/mol. From the given mass of each species, the moles of Mg and Br are 0.018 and 0.369 respectively. There are 2 Br in one Mg. The sample is MgBr2.
