To determine what elements are represented by the electron configuration given above, we need to know the sum of the exponents of each term or subshell involved in the configuration as this represent the atomic number of the element.
Atomic Number Element
<span>1s2 2s2 2p6: 2 + 2 + 6 = 10 neon
1s2 2s2 2p6 3s2 3p3: </span>2 + 2 + 6 + 2 + 3 = <span>15 phosphorus
1s2 2s2 2p6 3s2 3p6 4s1: </span>2 + 2 + 6 + 2 + 6+1 = <span>19 potassium
1s2 2s2 2p6 3s2 3p6 4s2 3d8: 20 + 8 = 28 nickel
1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d3: 30 + 6 + 2 +3 = 41 niobium</span>
Answer:
B
Explanation:
If something says always, you have to know for sure that it's true otherwise don't pick it. Covalent compounds have non-metals like carbon(s), oxygen(g), and bromine (l)
Answer: 138 J/K
Explanation:
1) ΔS reaction = ΔS products - ΔS reactants
2) ΔS products = 2ΔS Fe(s) + 3 ΔS H₂O (g)
3) ΔS reactants = ΔS Fe₂O₃ (s) + 3 ΔS H₂ (g)
4) Now you have to search the standard entropy values for each product and each reactant in a table.
I found these values at 25° and 1 bar.
ΔS H₂O = 188.8 J/Kₓmol
ΔS Fe(s) = 27.3 J/Kmol
ΔS Fe₂O₃ (s) = 87.4 J/Kmol
ΔS H₂ (g) = 130.7 J/Kmol
5) Replace those values into above equations:
ΔS products = 2ΔS Fe(s) + 3ΔS H₂O (g) =
2 mol × 27.3 J/K×mol + 3 mol ×188.8 J/K×mol = 621.0 J/K
ΔS reactants = ΔS Fe₂O₃ (s) + 3 ΔS H₂ (g) =
1mol × 87.4 J/K×mol + 3×130.7 J/K×mol = 479.5 J/K
ΔS reaction = 621.0 J/K - 479.5 J/K = 141.5 J/K
Taking into account the differences in the values from different sources (specially due to the temperature), you can consider that the value 141.5 J/K is pretty much close to 138 J/K, and take that answer.
Excess silicon dioxide" tells us carbon is the limiting reactant, and thus the amount of silicon carbide produced depends on how much carbon is available to react.
*Based on the balanced equation, for every 3 moles carbon reacted, 1 mole silicon carbide is produced.
*Molar mass carbon: 12.01 g/mol
*Molar mass silicon carbide: 28.09 g + 12.01 g = 40.1 g/mol
79.1 g carbon x (1 mol carbon / 12.01 g carbon) x (1 mol silicon carbide / 3 mol carbon) x (40.1 g silicon carbide / 1 mol silicon carbide) = 88.04 g silicon carbide