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1. Remember (sum of products) - (sum of reactants)
So ΔHrxn = 2 ΔHf [H2(g)] + ΔHf [Ca(OH)2(s)] - 2 ΔHf [H2O(l)] - ΔHf [Ca(s)]
= 2*0 + -986.09 kJ/mol - 2*(-285.8 kJ/mol) - 0
Do the math and you'll have the answer. BTW the ΔHf [H2(g)] and ΔHf
[Ca(s)] were 0 because these are elements in their standard states.
</span>HOPE THIS HELPS ;)
Answer:
Molar mass of Al2O3 = 101.961276 g/mol
This compound is also known as Aluminium Oxide.
Convert grams Al2O3 to moles or moles Al2O3 to grams
Molecular weight calculation:
26.981538*2 + 15.9994*3
Percent composition by element
Element Symbol Atomic Mass # of Atoms Mass Percent
Aluminium Al 26.981538 2 52.925%
Oxygen O 15.9994 3 47.075%
Explanation:
Percent composition by element
Element Symbol Mass Percent
Aluminium Al 52.925%
Oxygen O 47.075%
Explanation:
We can tell if a chemical reaction has taken place when one or more of the following things happen:
1.There has been a colour change inside the reaction flask.
2. A gas has formed. Usually we know a gas has formed when we can see bubbles.
3.A solid has formed.
hope this answer helps!!!
Answer:
the earth is tilted towards the sun
Explanation:
In the context, there is a sun and earth system and at a certain point when the earth is moving in its orbit around he sun, some point on the earth experiences the summers season. This is because at this point of the earths revolution, the point on the earth is facing the sun and is also tilted towards the sun. So at this point the sun rays fall directly at the surface. While the place which is tilted away from the sun, experiences winter season.
Answer: last one is right
Explanation: atoms of same element have always same number of protons but may have several isotopes which have different number of neutrons.