Answer:
A. Samuel
Explanation:
although he is not right he gets the same measurement several times
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.
Answer:
B There are two grams of hydrogen for each gram of carbon in this compound.
Explanation:
The second option is a wrong interpretation of this chemical representation of formaldehyde.
Formaldehyde is an organic compound with the formula CH₂O.
As this is the simplest formula of the compound, it is the empirical formula. Also, the formula is the actual one for the compound and it is the molecular formula.
Chemically, the formula shows 1 mole of carbon, 2 moles of H and 1 mole of oxygen in the compound.
- A mole of a substance is more a less a unit of measurement in chemistry and it is the amount of substance that contains the avogadro's number of particles.
This ratio is not the mass of chemical species in the compound. You cannot tell the mass of elements in a compound by merely looking at the formula.
Answer:
Water, in either liquid or solid form, is often a key agent of mechanical weathering. For instance, liquid water can seep into cracks and crevices in rock. If temperatures drop low enough, the water will freeze. ... This specific process (the freeze-thaw cycle) is called frost weathering or cryofracturing.
