Answer:
n = 3
Explanation:
Given the formula for the transition energy of an atom with 1 electron:
For the H transition n=5 to n=2:
Then we solve for nf with Z=2 (Helium)
Is near 3, actually the energy of the transitions are:
H (5⇒2) = -2.85 eV = 434 nm (Dark blue)
He (4⇒3) = -2.64 eV = 469 nm (Light blue)
I thought it was cool to see the actual colors. Included them.
A double displacement reaction is one in which the positive and negative ion in one reactant switch places with the positive and negative ions of the second reactant forming two new products.
In general if we have two reactants AB and CD, the double displacement reaction can form the following products:
A⁺B⁻ + C⁺D⁻ → C⁺B⁻ + A⁺D⁻
In the given example:
K₂SO₄ + Pb(NO₃)₂ → PbSO₄ + 2KNO₃
Ans: B)
One of the products would be PbSO₄
Answer:
The theoretical yield of
Li
3
N
is
20.9 g
.
Explanation:
Balanced Equation
6Li(s)
+
N
2
(
g
)
→
2Li
3
N(s)
In order to determine the theoretical yield, we must first find the limiting reactant (reagent), which will determine the greatest possible amount of product that can be produced.
Molar Masses
Li
:
6.941 g/mol
N
2
:
(
2
×
14.007
g/mol
)
=
28.014 g/mol
Li
3
N
:
(
3
×
6.941
g/mol Li
)
+
(
1
×
14.007
g/mol N
)
=
34.83 g/mol Li
3
N
Limiting Reactant
Divide the mass of each reactant by its molar mass, then multiply times the mole ratio from the balanced equation with the product on top and the reactant on bottom, then multiply times the molar mass of
Li
3
N
.
Lithium
12.5
g Li
×
1
mol Li
6.941
g Li
×
2
mol Li
3
N
6
mol Li
×
34.83
g Li
3
N
1
mol Li
3
N
=
20.9 g Li
3
N
Nitrogen Gas
34.1
g N
2
×
1
mol N
2
28.014
g N
2
×
2
mol Li
3
N
1
mol N
2
×
34.83
g Li
3
N
1
mol Li
3
N
=
84.8 g Li
3
N
Lithium produces less lithium nitride than nitrogen gas. Therefore, the limiting reactant is lithium, and the theoretical yield of lithium nitride is
20.9 g
.
Explanation:
