Answer:
0.87mole
Explanation:
The reaction equation is given as;
4Fe + 3O₂ → 2Fe₂O₃
Number of moles of Fe₂O₃ in 138.5g
To solve this problem;
Number of moles =
Molar mass of Fe₂O₃ = 2(56) + 3(16) = 160g/mol
Now;
Number of moles =
= 0.87mole
Answer:
![\delta=101.13 g/cm^3](https://tex.z-dn.net/?f=%5Cdelta%3D101.13%20g%2Fcm%5E3)
Explanation:
As can be seen in the Figure in a face-centered cubic unit cell you have:
- Six halves of atoms
- Eight 1/8 of atom (1 in each corner)
In total:
![n_{atom}=6*0.5+8*\frac{1}{8}=4 atoms](https://tex.z-dn.net/?f=n_%7Batom%7D%3D6%2A0.5%2B8%2A%5Cfrac%7B1%7D%7B8%7D%3D4%20atoms)
Now, each side of the cell is 234 picometers (2.34e-8 cm) long
![V_{cell}=L^3=(2.34e^{-8} cm)^3](https://tex.z-dn.net/?f=V_%7Bcell%7D%3DL%5E3%3D%282.34e%5E%7B-8%7D%20cm%29%5E3)
![V_{cell}=1.28*10^{-23}cm^3](https://tex.z-dn.net/?f=V_%7Bcell%7D%3D1.28%2A10%5E%7B-23%7Dcm%5E3)
Atoms per cm3:
![n=\frac{4 atoms}{1.28*10^{-23}cm^3}](https://tex.z-dn.net/?f=n%3D%5Cfrac%7B4%20atoms%7D%7B1.28%2A10%5E%7B-23%7Dcm%5E3%7D)
![n=3.12*10^{23} atoms/cm^3](https://tex.z-dn.net/?f=n%3D3.12%2A10%5E%7B23%7D%20atoms%2Fcm%5E3)
Expressing in mass:
![\delta=3.12*10^{23} atoms/cm^3* \frac{1 mol}{6.022*10^{23}}*195.08 g/mol](https://tex.z-dn.net/?f=%5Cdelta%3D3.12%2A10%5E%7B23%7D%20atoms%2Fcm%5E3%2A%20%5Cfrac%7B1%20mol%7D%7B6.022%2A10%5E%7B23%7D%7D%2A195.08%20g%2Fmol)
![\delta=101.13 g/cm^3](https://tex.z-dn.net/?f=%5Cdelta%3D101.13%20g%2Fcm%5E3)
Answer:
no of moles = (mass) ÷ molar mass
you get the molar mass from the periodic table
n = 20.0g ÷ ( 149.09 g/mol )
= 0.134 mol
number of formula units = number of moles × (6.022×10^23)
= 8.07×10^22 units
number of hydrogen atoms in (NH4)3 PO3 = 12 × number of formula units
= 9.68×10^23 hydrogen atoms
Answer:
0.0794 L
Explanation:
An experiment requires 62.7 g of ethyl alcohol. The density of ethyl alcohol is 0.790 g/mL. The volume, in milliliters, corresponding to 62.7 g of ethyl alcohol is:
62.7 g × (1 mL/0.790 g) = 79.4 mL
1 liter is equal to 1000 milliliters. The volume, in liters, corresponding to 79.4 mL is:
79.4 mL × (1 L/ 1000 mL) = 0.0794 L