Answer:
Helium is in group 18 of the periodic table. How is helium different from the other elements in this group? = Helium atoms have 2 valence electrons, while atoms of the other elements in the group all have 8 valence electrons.
An emission spectrum will occur when = An electron releases energy and falls back to a lower energy level.
Explanation:
The number of protons in an atom is equal the atomic number (= 50)
The sum of the Neutrons and Protons is the Atomic Mass (=125)
Neutrons + Protons=125
Plug in for the protons (50)
Neutrons +(50)=125
Then, once solved, we have Neutrons = 75
Assuming the atom is NOT an ion, the amount of electrons is equal to the number of protons. (protons=electrons=50=50)
Therefore:
There are 50 electrons, 50 protons, and 75 electrons.
Given: C3H8(g) + O2(g) ----> CO2 (g) + H2O (g)
Step : Put a 3 in front of CO2 (g) to balance C
=> C3H8(g) + O2(g) ----> 3CO2 + H2O to balance H
Step 2: Put a 4 in front of H2O
=> C3H8 (g) + O2(g) -----> 3CO2 (g) + 4H2O (g)
Step 3: Given that there are 3*2 + 4 = 10 O to the right side, put a 5 in front of O2 to balance O:
=> C3H8(g) + 5O2(g) -----> 3CO2(g) + 4H2O(g)
You can verify that the equation is balanced.
So, the answer is that the coefficient in front of O2 is 5.
Answer: 14.1g
Explanation:
Given that,
number of moles of SiO2 = 0.235 moles
Mass in grams = Z (let unknown value be Z)
Molar mass of SiO2 = ?
To get the molar mass of SiO2, use the atomic mass
Silicon = 28g;
Oxygen = 16g
i.e Molar mass of SiO2 = 28g + (16g x 2)
= 28g + 32g
= 60g/mol
Now, apply the formula
Number of moles = Mass / molar mass
0.235 moles = Z / 60g/mol
Z = 0.235 moles x 60g/mol
Z = 14.1 g
Thus, the mass of SiO2 is 14.1 grams.
