Explanation:
The electrons in the outermost shell of an atom are the valence electrons. These electrons are the most loosely held in an atom.
The energy required to remove these electrons are not as great as those of the inner shell electrons.
- Atoms of some elements show no tendency to combine with other atoms because they have completely filled outer energy levels.
- Their outermost shell, valence shell and the electron numbers are complete for them. These are the noble gases.
- other atoms share or exchange their valence electrons in order to have a stable configuration.
- The valence electrons are involve in inter-atomic bond formation and interactions
- Also the distribution of these electrons determines inter-molecular interactions between molecules.
Learn more:
valence electrons in metalloids brainly.com/question/3023499
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Answer:
copper
Explanation:
it's on the periodic table of elements
Answer: 72.4 kJ/mol
Explanation:
The balanced chemical reaction is,
The expression for enthalpy change is,
![\Delta H=\sum [n\times \Delta H_f(product)]-\sum [n\times \Delta H_f(reactant)]](https://tex.z-dn.net/?f=%5CDelta%20H%3D%5Csum%20%5Bn%5Ctimes%20%5CDelta%20H_f%28product%29%5D-%5Csum%20%5Bn%5Ctimes%20%5CDelta%20H_f%28reactant%29%5D)
![\Delta H=[(n_{CO_2}\times \Delta H_{CO_2})+(n_{H_2O}\times \Delta H_{H_2O})]-[(n_{O_2}\times \Delta H_{O_2})+(n_{C_3H_8}\times \Delta H_{C_3H_8})]](https://tex.z-dn.net/?f=%5CDelta%20H%3D%5B%28n_%7BCO_2%7D%5Ctimes%20%5CDelta%20H_%7BCO_2%7D%29%2B%28n_%7BH_2O%7D%5Ctimes%20%5CDelta%20H_%7BH_2O%7D%29%5D-%5B%28n_%7BO_2%7D%5Ctimes%20%5CDelta%20H_%7BO_2%7D%29%2B%28n_%7BC_3H_8%7D%5Ctimes%20%5CDelta%20H_%7BC_3H_8%7D%29%5D)
where,
n = number of moles
(as heat of formation of substances in their standard state is zero
Now put all the given values in this expression, we get
![-2220.1=[(3\times -393.5)+(4\times -241.8)]-[(5\times 0)+(1\times \Delta H_{C_3H_8})]](https://tex.z-dn.net/?f=-2220.1%3D%5B%283%5Ctimes%20-393.5%29%2B%284%5Ctimes%20-241.8%29%5D-%5B%285%5Ctimes%200%29%2B%281%5Ctimes%20%5CDelta%20H_%7BC_3H_8%7D%29%5D)
Therefore, the heat of formation of propane is 72.4 kJ/mol
Answer:
(a) weight percent of Cu = 44.59%
(b) weight percent of Zn = 53.49%
(c) weight percent of Pb = 1.91%
Explanation:
Given: Alloy contains- Cu=93.1 g, Zn=111.7 g, Pb=4.0 g
Therefore, the total mass of the alloy (m) = mass of Cu (m₁) + mass of Zn (m₂)+ mass of Pb (m₃)
m= 93.1 g + 111.7 g + 4.0 g = 208.8 g
(a) weight percent of Cu = (m₁ ÷ m)× 100% = (93.1 g ÷ 208.8 g)× 100% =44.59%
(b) weight percent of Zn = (m₂ ÷ m)× 100% = (111.7 g ÷ 208.8 g)× 100% =53.49%
(c) weight percent of Pb = (m₃ ÷ m)× 100% = (4.0 g ÷ 208.8 g)× 100% =1.91%
Answer: 7.56 moles
Explanation:
C3H8 is the chemical formula for propane, the third member of the alkane family.
Recall that based on Avogadro's number, 1 mole of any substance has 6.02 x 10^23 atoms
So 1 mole of C3H8 = 6.02 x 10^23 atoms
Z moles of C3H8 = 4.55 x 10^24 atoms
To get the value of Z, we cross multiply:
1 x 4.55 x 10^24 atoms = Z moles x (6.02 x 10^23 atoms)
4.55 x 10^24 atoms = Z moles x (6.02 x 10^23 atoms)
To get the value of Z divide both sides by 6.02 x 10^23 atoms
Z moles =4.55 x 10^24 atoms ➗ 6.02 x 10*23 atoms
Hence, Z = 7.56 moles
Thus, the number of propane, C3H8 is 7.56 moles
