Which statement best describes what happens during a chemical change
2 answers:
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Answer:
Explanation:
Electronic configuration represents the total number of electrons that a neutral element contains. We add all the superscripts to know the number of electrons in an atom.
The electrons are filled according to Afbau's rule in order of increasing energies and thus the electronic configuration for Hafnium with atomic number of 72 and containing 72 electrons is:
The electronic configuration for Hafnium in terms of nearest noble gas Is
Considering the definition of molar mass, the number of moles of Zn reactant used is 2 moles.
<h3>Definition of molar mass</h3>The molar mass of substance is a property defined as its mass per unit quantity of substance, in other words, molar mass is the amount of mass that a substance contains in one mole.
<h3>Number of moles of Zn used</h3>The balanced reaction is:
Zn(s) + 2 HCl(aq) → ZnCl₂ + H₂(g)
Assume that 130.8 grams of Zn was used in this reaction.
To determine the number of moles of hydrogen gas formed, you need to know the number of moles of Zn reactant was used.
So to determine the number of moles used you know that the molar mass of Zn is 65.37. Then:
Solving:
number of moles× 65.37= 130.8 g
<u><em>number of moles≅ 2 moles</em></u>
Finally, the number of moles of Zn reactant used is 2 moles.
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