Answer:
the correct answer is option A copper and silver
Answer:
1. 0.125 mole
2. 42.5 g
3. 0.61 mole
Explanation:
1. Determination of the number of mole of NaOH.
Mass of NaOH = 5 g
Molar mass of NaOH = 23 + 16 + 1
= 40 g/mol
Mole of NaOH =?
Mole = mass /molar mass
Mole of NaOH = 5/40
Mole NaOH = 0.125 mole
2. Determination of the mass of NH₃.
Mole of NH₃ = 2.5 moles
Molar mass of NH₃ = 14 + (3×1)
= 14 + 3
= 17 g/mol
Mass of NH₃ =?
Mass = mole × molar mass
Mass of NH₃ = 2.5 × 17
Mass of NH₃ = 42.5 g
3. Determination of the number of mole of Ca(NO₃)₂.
Mass of Ca(NO₃)₂ = 100 g
Molar mass of Ca(NO₃)₂ = 40 + 2[14 + (3×16)]
= 40 + 2[14 + 48]
= 40 + 2[62]
= 40 + 124
= 164 g/mol
Mole of Ca(NO₃)₂ =?
Mole = mass /molar mass
Mole of Ca(NO₃)₂ = 100 / 164
Mole of Ca(NO₃)₂ = 0.61 mole
The molar mass of Ca(ClO4)2 is 239.1 g/mol.
When Cr+3 + 3e- → Cr(s)
So according to the charge formula:
charge Q = I * t
when we have I (the current) = 7.4 a
and t (the time in seconds) = 1.85d * 24h * 60 min*60sec= 159840 sec
by substitution:
Q = 7.4 a * 159840 sec = 1182816 C
now to get the mass we have to use Faraday constant which is:
F = e NA
= 1.602 x 10^-19 * 6.022 x 10^23
= 96485 C mol^-1
when e is the electron charge & NA Avogadro's number for the charge in on mol
and as we can see from the equation Cu3+ reacts with 3 electrons so,
the mass of Cr(s) = Q* (1mole-/F) * (1molCr / 3 mol e-)
= 1182816 * (1/96485) * (1/3)
= 4.1 g
