Suppose a metal will eject electrons from its surface when struck by yellow light. What will happen if the surface is struck wit
1 answer:
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Nitrogen lone pair will act as a base,removing H+ from water leaving behind OH- ion.
Why ?
Because N is a better donor than O.
Answer :
The enthalpy of reaction is, -187.6 kJ/mol
The total heat will be, -2251 kJ
Explanation :
According to Hess’s law of constant heat summation, the heat absorbed or evolved in a given chemical equation is the same whether the process occurs in one step or several steps.
According to this law, the chemical equation can be treated as ordinary algebraic expression and can be added or subtracted to yield the required equation. That means the enthalpy change of the overall reaction is the sum of the enthalpy changes of the intermediate reactions.
(a) The formation of will be,
The intermediate balanced chemical reaction will be,
(1)
(2)
(3)
We are multiplying equation 1 by 2 and then adding all the equations, we get :
(b) The expression for enthalpy of reaction will be,
Therefore, the enthalpy of reaction is, -187.6 kJ/mol
(c) Now we have to calculate the total heat.
or,
where,
= enthalpy change = -187.6 kJ/mol
q = heat = ?
n = number of moles of coal =
Now put all the given values in the above formula, we get:
Thus, the total heat will be, -2251 kJ
Answer:
A scandium-48 nucleus undergoes beta-minus decay to produce a titanium-48 nucleus.
.
Explanation:
There are two types of beta decay modes: beta-minus and beta-plus.
In both decay modes, the mass number of the nucleus stays the same.
However, in a beta-minus decay, the atomic number of the nucleus increases by one. In a beta-plus decay, the atomic number decreases by one.
Each beta-minus decay releases one electron and one electron antineutrino. Each beta-plus decay releases one positron and one electron neutrino.
Look up the atomic number and relative atomic mass for the element scandium.
- The atomic number of
is
.
- The relative atomic mass of
.
This question did not specify whether the decay here is beta-plus or a beta-minus. However, the relative atomic mass of this element can give a rough estimate of the mode of decay.
Each element (e.g, ) can have multiple isotopes. These isotopes differ in mass. The relative atomic mass of an element is an average across all isotopes of this element. This mass is weighted based on the relative abundance of the isotopes. Its value should be closest to the most stable (and hence the most abundant) isotope.
The mass number of scandium-48 is significantly larger than the relative atomic mass of this element. In other words, this isotope contains more neutrons than isotopes that are more stable. There's a tendency for that neutron to convert to a proton- by beta-minus decay, for example.
The atomic number of the nucleus will increase by 1. . That corresponds to titanium. The mass number stays the same at
. Hence the daughter nucleus would be titanium-48. Note that two other particles: one electron and one electron
and one antineutrino
(note the bar.) The neutrino helps balance the lepton number of this reaction.