Answer:
8 valence electrons
Explanation:
There are 4 valence electrons in carbon because it is in group 4A of the periodic table. There is 1 valence electron per hydrogen based on its position on the periodic table, but CH4 has 4 hydrogens in it. So 1 times 4 is 4. Add the 4 valence electrons from carbon with the 4 electrons from H4 to get 8.
Answer:
6.82g
0.59moles
Explanation:
1. What is the mass sample of 0.0500 moles of zinc chloride ?
Given parameters:
Number of moles ZnCl₂ = 0.05moles
Unknown:
Mass of the sample = ?
Solution:
To find the mass of a substance using the number of moles, it would be pertinent to understand what mole is.
A mole is a substance that contains the avogadro's number of particles.
It relates to the mass using the expression below;
Mass of a substance = number of moles x molar mass
Molar mass of ZnCl₂;
Atomic mass of Zn = 65.4g/mol
Cl = 35.5g/mol
Molar mass = 65.4 + 2(35.5) = 136.4g/mole
Mass of a substance = 0.05 x 136.4 = 6.82g
2. How many moles of potassium sulfide are in a 65.50g sample?
Given parameters:
Mass of K₂S = 65.5g
Unknown:
Number of moles = ?
Solution:
The number of moles of any substance is related to mass using the expression below;
Number of moles =
Molar mass of K₂S = 2(39) + 32 = 110g/mol
Number of moles = = 0.59moles