A beaker of black powder can be a mixture with different substances (i.e gunpowder: a mixture of sulfur, charcoal, etc.), an element which can probably be carbon (known as black), and a compound as well which can be potassium nitrate. Hence, the answer is D.
Answer:
Graph A.
Explanation:
Graph
It represents a constant function
43.8 kJ
<h3>
Explanation</h3>
There are two electrodes in a voltaic cell. Which one is the anode?
The lithium atom used to have no oxygen atoms when it was on the reactant side. It gains two oxygen atoms after the reaction. It has gained more oxygen atoms than the manganese atom. Gaining oxygen is oxidation. As a result, lithium is being oxidized.
Oxidation takes place at the anode of a cell. Therefore, the anode of this cell is made of lithium.
Lithium has an atomic mass of 6.94. Each gram of Li would contain 1/6.94 = 0.144 moles of Li atoms. Each Li atom loses one electron in this cell. Therefore, the number of electron transferred, <em>n</em>, equals 0.144 moles for each gram of the anode.
Let 
represents the electrical energy produced.
, where
- <em>n</em> is the <em>number of moles</em> electrons transferred,
- <em>F</em> is the Faraday's constant,
- <em>E</em>
is the cell potential,
<em>n </em>= 0.144 mol, as shown above, and
<em>F </em>= 96.486 kJ / (
).
Therefore,
.
The energy change if 84.0 g of CaO react with excess water is 98KJ of heat is released.
calculation
heat = number of moles x delta H
delta H = - 65.2 Kj/mol
first find the number of moles of CaO reacted
moles = mass/molar mass
the molar mass of CaO = 40 + 16= 56 g/mol
mass = 84 g
moles therefore = 84 g/56 g/mol =1.5 moles
Heat is therefore = 1.5 moles x -65.2 = - 97.8 Kj = -98 Kj
since sign is negative the energy is released
In atomic physics and quantum chemistry, the electron configuration is the distribution of electrons of an atom or molecule (or other physical structure) in atomic or molecular orbitals. For example, the electron configuration of the neon atom is 1s² 2s² 2p⁶, using the notation explained below.
