Answer:
-) Lewis structure: See the figure 1
-) Oxidation number of As = +5
-) Oxidation number of O = -2
Explanation:
The first step is to calculate the <u>total amount of electrons</u>, for As we will have 5 electrons, for all the oxygens we will have 24 electrons (6 electrons for each atom) and finally we will have 3 more due to the charge (-3), so in total we will have: 5+24+3= 32 electrons.
In the lewis structure, we will have as <u>central atom</u> "As" then we have to put the oxygens around the central atom. In this case, As is an <u>exception of the octet rule</u>, in this structure As would have 10 electrons and 8 electrons for each oxygen. So, in the total distribution of the electrons in the structure, we will have the 32 electrons that we calculate in the first step (figure 1).
Finally, in the oxidation number calculation, we have to start with the oxidation number of oxygen. <u>The oxidation number of O is -2</u> then when we <u>multiply by the number of atoms</u> we will get -8, so the As must have an oxidation number of +5 in order to obtain a total charge of -3 (figure 2).
The change is thermal energy to chemical energy. Sugar contains a lot of chemical potential energy which is why living things use it as a source of energy. The process of photo synthesis takes light from the sun to convert carbon dioxide and water into sugar and oxygen. That process is basically turning the thermal energy from the light into chemical energy in the sugar.
Answer:
18.52g
Explanation:
(relative atomic masses: H = 1.01, O = 16.00, Ca = 40.08)
Equation (balanced):
Ca + 2H2O -> Ca(OH)2 +H2
First, calculate the number of moles of 10g calcium
No. of moles of Ca = 10/40.08 = 0.25 mol
Then, calculate the number of moles of 20g water
No of moles of H2O = 1.11 mol
According to the balanced equation, 1 mole of calcium reacts with 2 moles of H2O completely. Therefore, H2O is in excess.
So, 1 mole of calcium reacts with water to form 1 mole of Ca(OH)2 (according to the mole ratio shown in the balanced equation)
Therefore, 0.25 mol of Ca(OH)2 is produced.
Mass of Ca(OH)2 produced = no. of moles x molar mass = 0.25 x (40.08 + 16 + 16 + 1.01 + 1.01) = 18.52g
Good luck!
The Law of Conservation of Mass dates from Antoine Lavoisier's 1789 discovery that mass is neither created nor destroyed in chemical reactions. ... If we account for all reactants and products in a chemical reaction, the total mass will be the same at any point in time in any closed system.