Answer:
7.28 mol Na2SO4
Explanation:
Since it is already in moles, all we have to do is use a molar ratio
A molar ratio is the proportions of reactants and products using the balanced equation. When writing a mole ratio, the given information must cross out with the right thing.
7.28 mol H2SO4 * 1 mol Na2SO4/1 H2SO4 = 7.28 mol Na2SO4
*notice how the H2SO4 crosses out
Answer:
D. Ni²⁺
Explanation:
We know at once that the answer cannot be A or C, because Ni and Cu are already in their lowest oxidation states.
The correct answer must be either B or D.
An electrolytic cell is the opposite of a galvanic cell. In the former, the reaction proceeds spontaneously. In the latter, you must force the reaction to occur.
One strategy to solve this problem is:
- Look up the standard reduction potentials for the half reaction·
- Figure out the spontaneous direction.
- Write the equation in the reverse direction.
1. Standard reduction potentials
E°/V
Cu²⁺ + 2e⁻ ⟶ Cu; 0.3419
Ni²⁺ + 2e⁻ ⟶ Ni; -0.257
2. Galvanic Cell
We reverse the direction of the more negative half cell and add.
<u>E°/V
</u>
Ni ⟶ Ni²⁺ + 2e⁻; 0.257
<u>Cu²⁺ + 2e⁻ ⟶ Cu; </u> 0.3419
Ni + Cu²⁺ ⟶ Cu + Ni²⁺; 0.599
This is the spontaneous direction.
Cu²⁺ is reduced to Cu.
3. Electrochemical cell
<u>E°/V</u>
Ni²⁺ + 2e⁻ ⟶ Ni; -0.257
<u>Cu ⟶ Cu²⁺ + 2e⁻; </u> <u>-0.3419</u>
Cu + Ni²⁺ ⟶ Ni + Cu²⁺; -0.599
This is the non-spontaneous direction.
Ni²⁺ is reduced to Ni in the electrolytic cell.
The grams of FeO that would be needed to make 234.2 grams of Fe is
1204.42 grams
<u><em> calculation</em></u>
4 FeO → Fe₃O₄ +Fe
Step 1: find the moles of fe
moles = mass /molar mass
from periodic table the molar mass of Fe = 56 g/mol
moles = 234.2 g/56 g/mol = 4.182 moles
Step 2: use the mole ratio to determine the moles of FeO
FeO: Fe is 4:1 therefore the moles of FeO =4.182 moles x4 =16.728 moles
Step 3: find the mass of FeO
mass = moles x molar mass
The molar mass of FeO = 56 +16 = 72 g /mol
mass = 16.728 moles x 72 g/mol= 1204.42 grams
Answer:
34.9103 or 34.9 g
Explanation:
Remember Density is a broken heart: m/v.
In this scenario (Let x = # of grams in the sample of gasoline),
D = 0.7198 g/mL = x g / 48.5 mL
So,
(0.7198 g/mL) * (48.5 mL) = x g
x g = 34.9103 = 34.9 g (Accounting for Significant Figures)
So in order to answer this we need the number of moles of oxygen and the right stoichiometry.
The balanced reaction should be 2HgO --> 2Hg + O2, therefore 2 moles of mercury are produced for every one mole of oxygen gas. Since we have the mass of O2 we can calculate the moles as moles = mass/RMM where RMM is the relative molecular mass of O2, which is 32 g/mol. Therefore the number of moles = 125/16 = 3.9 mol.
Since 2 moles of Hg are produced for every one mole of O2, the number of moles of Hg = 3.9*2 = 7.8 mol.
