We subtract the enthalpies of the reactants from that of the products:
Since this is < 0, this is an exothermic reaction.
Answer:
what does it say under the paragraph
Explanation:
1.59moles
Explanation:
Mass of CaO = 89.23g
Unknown
Number of moles = ?
Solution:
The mole is a unit of measurement in chemistry used to delineate the number of particles an atom contains.
A mole of a substance contains the avogadro's number of particles.
Number of moles = 
Molar mass of CaO = 40 + 16 = 56g/mol
Number of moles = 
= 1.59moles
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Answer:
Isotopes are variants of an element, where the number of neutrons is different but its number of protons stay the same.
Explanation:
If the number of protons had changed then it would just be a different element.
Electron number changing simply adds charge to the atom, and doesn't change it or anything.
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Answer:
The mass of an atom is found in its nucleus.
Explanation:
An atom is made of three different particles: protons, neutrons and electrons.
Protons (positive charge) and neutrons (no charge) each have a mass of 1 AMU. They are both found in the nucleus (centre) of the atom.
Electrons (negative charge) are considered to have a mass of 0. Their mass is not actually 0, but very close so we do not count them. They are not in the nucleus, but found in shells surrounding the atom.
To calculate the mass of an atom, we add the number of protons and the number of electrons.
m = P + N
