Answer:
172 g Al
Step-by-step explanation:
We know we will need a balanced equation with masses and molar masses, so let’s <em>gather all the information</em> in one place.
M_r: 26.98 101.96
4Al + 3O₂ ⟶ 2Al₂O₃
m/g: 325
(a) Calculate the <em>moles of Al₂O₃
</em>
n = 325 g Al₂O₃ × 1 mol Al₂O₃ /39.10 g Al₂O₃
n = 3.188 mol Al₂O₃
(b) Calculate the <em>moles of Al
</em>
The molar ratio is (4 mol Al/2 mol Al₂O₃)
n = 3.188 mol Al₂O₃ × (4 mol Al/2 mol Al₂O₃)
n = 6.375 mol Al
(c) Calculate the <em>mass of Al</em>
m = 6.375 mol Al × (26.98 g Al/1 mol Al)
m = 172 g Al
Note: The answer can have only <em>three</em> significant figures because that is all you gave for the mass of Al₂O₃.
Answer:
oxygen should be the central atom in the middle
Explanation:
hydrogens always go on the outside
Answer:
5 g
Explanation:
The heat required to vaporize ice is the sum of
i) Heat required to melt ice at 0°C
ii) Heat required to raise the temperature from 0°C to 100°C
iii) Heat required to vaporize water at 100°C
Thus;
H = nLfus + ncθ + nLvap
H= n(Lfus + cθ + Lvap)
Lfus = 6.01 kJ/mol
Lvap = 41 kJ/mol
c = 75.38
n =?
2100 = n(6.01 + 75.38(100) + 41)
n = 2100 KJ/7585.01 kJ/mol
n = 0.277 moles
Mass of water = number of moles * molar mass
Mass of water = 0.277 moles * 18 g/mol
Mass of water = 5 g
Answer:
0.053moles
Explanation:
Hello,
To calculate the number of moles of gas remaining in his after he exhale, we'll have to use Avogadro's law which states that the volume of a given mass of gas is directly proportional to its number of moles provided that temperature and pressure are kept constant. Mathematically,
V = kN, k = V / N
V1 / N1 = V2 / N2= V3 / N3 = Vx / Nx
V1 = 1.7L
N1 = 0.070mol
V2 = 1.3L
N2 = ?
From the above equation,
V1 / N1 = V2 / N2
Make N2 the subject of formula
N2 = (N1 × V2) / V1
N2 = (0.07 × 1.3) / 1.7
N2 = 0.053mol
The number of moles of gas in his lungs when he exhale is 0.053 moles
