Number of moles of oxygen = x
number of moles of nitrogen = y
x = 2y
initial pressure, p1 = 0.8 atm
final pressure, p2 = 1.10 atm
At constant volume and temperature p1 / n1 = p2 / n2
=> p1 / p2 = n1 / n2
n1 = x + y = 2y + y = 3y
n2 = 0.2 + 3y
=> p1 / p2 = 3y / (0.2 + 3y)
=> 0.8 / 1.10 = 3y / (0.2 + 3y)
=> 0.8 (0.2 + 3y) = 1.10 (3y)
0.16 + 2.4y = 3.3y
=> 3.3y - 2.4y = 0.16
=> 0.9y = 0.16
=> y = 0.16 / 0.9
=. x = 2*0.16/0.9 = 0.356
Answer: 0.356 moles O2
Answer is: A. 1.1 3 1023 NiCl2 formula units.
m(NiCl₂) = 24.6 g; mass of nickel(II) chloride.
M(NiCl₂) = 129.6 g/mol; molar mass of nickel(II) chloride.
n(NiCl₂) = m(NiCl₂) ÷ M(NiCl₂).
n(NiCl₂) = 24.6 g ÷ 129.6 g/mol.
n(NiCl₂) = 0.19 mol; amount of nickel(II) chloride.
Na = 6.022·10²³ 1/mol; Avogadro constant.
N(NiCl₂) = n(NiCl₂) · Na.
N(NiCl₂) = 0.19 mol · 6.022·10²³ 1/mol.
N(NiCl₂) = 1.13·10²³; number of formula units.
<span>1.86 moles of hydrogen gas.
Since what the HCl is reacting with hasn't been mentioned, I'll assume zine. In that case, the balanced reaction is
Zn + 2HCl ==> ZnCl2 + H2
So for every 2 moles of HCl used, 1 mole of hydrogen gas will be generated. So let's figure out how many moles of HCl we have and then divide by 2.
Molarity is defined as moles/liter. So a 2.75 M HCl solution has 2.75 moles of HCl per liter. So the total number of moles we have is:
2.75 mole/L * 1.35 L = 3.7125 mol
And since we get 1 mole H2 per mole of HCl, we get:
3.7125 mol / 2 = 1.85625 mol
Rounding to 3 significant figures gives us 1.86 moles of hydrogen gas.</span>
