A magnesium atom is a neutral atom where the number of protons and electrons are the same. A magnesium ion has a positve 2 charge since it will lose two of its electrons when it undergoes ionic bonding. Since it's the same element it will still have the same amount of 12 protons. For isotopes of magnesium, they will have differing amounts of neutrons and thus a difference in the mass number since neutrons have a mass of about 1
Answer:
The correct answer is 596.5 kJ.
Explanation:
The mass of ethanol or C2H5OH mentioned in the question is 20 gm.
The molar mass of ethanol is 46 g/mol.
The moles of the compound can be determined by using the formula,
n = weight of the compound/molar mass
= 20/46 = 0.435 moles
It is mentioned in the question that standard heat of combustion of ethanol is 1372 kJ/mole, that is, one mole of ethanol is producing 1372 kilojoules of energy at the time of combustion.
Therefore, the energy liberated by completely burning the 20 grams of ethanol is 0.435*1372 = 596.5 kJ.
I can't remember any of the weights of the individual elements but here is how you solve it:
Molecular weight of copper + nitrogen + 3 oxygens = molecular weight of the compound.
M = moles / liter
.350 moles / 1 liter
Do .350 moles / liter x the molecular weight (g / mole) of the compound = the answer in g / L
