Answer:
The number of valence electrons can be known from the group that the element is in (except the lanthanides, actinides and groups 3-12).
Explanation:
Group 1 has 1 valence electron. Group 2 has 2 valence electrons. Group 13 has 3 valence electrons. Group 14 has 4, group 15 has 5, group 16 has 6, group 17 has 7, and group 18 has 8.
Group 18 are the noble gases which are stable.
Group 17 are the halogens and react well with the alkali metals.
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Answer: 35.1 kJ/mol
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.
(1)
(1)
The final reaction is:
(3)
By adding (1) and (2)
Hence the expected value for the heat of sublimation of acetic acid is 35.1 kJ/mol
The mass number of element is 22.
The mass number is the sum of number of electrons/proton and number of neutron .
Mass number = number of proton/electron + number of neutrons
If an element with 11 neutrons, 11 protons, and 11 electrons then mass number is calculated as,
Mass number = number of proton/electron + number of neutrons
Mass number = 11 + 11 = 22
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Answer:
<h2>69.3 g</h2>
Explanation:
The mass of a substance when given the density and volume can be found by using the formula
mass = Density × volume
From the question we have
volume = 55 mL
density = 1.26 g/mL
mass = 1.26 × 55 = 69.3 g
We have the final answer as
<h3>69.3 g</h3>
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