Answer: CrO₄⁻ and Ba²⁺
Explanation:
1) Chemical equation given:
2H⁺ + CrO₄⁻ + Ba²⁺ + 2OH⁻ → Ba²⁺ + CrO₄⁻ + 2H₂O
2) Analysis
That is an oxidation-reduction equation (some species are been oxidized and others are being reduced).
The given equation is known as total ionic equation, because it shows all the species as ions that are part of the reaction.
2) Specator ions
Spectator ions are the ions that do not change their oxidation state and are easily identified as they are the same in the reactant and product sides.
Here the ions that are the same in the reactant and product sides are:
CrO₄⁻ and Ba²⁺
3) Addtitional explanation.
Once you identify the spectator ions you can delete them from the equation to obtain the net ionic equation , which in this case turns to be:
2H⁺ + 2OH⁻ → 2H₂O
But this is not part of the question; it is some context to help you understand the use of the spectator ions concept.
Answer:
Thomson placed two magnets on either side of the tube, and observed that this magnetic field also deflected the cathode ray. The results of these experiments helped Thomson determine the mass-to-charge ratio of the cathode ray particles, which led to a fascinating discovery, minus the mass of each particle was much, much smaller than that of any known atom. Thomson repeated his experiments using different metals as electrode materials, and found that the properties of the cathode ray remained constant no matter what cathode material they originated from. From this evidence, Thomson made the following conclusions:
The cathode ray is composed of negatively-charged particles.
The particles must exist as part of the atom, since the mass of each particle is only ~1/2000 the mass of a hydrogen atom.
These subatomic particles can be found within atoms of all elements.
While controversial at first, Thomson's discoveries were gradually accepted by scientists. Eventually, his cathode ray particles were given a more familiar name: electrons. The discovery of the electron disproved the part of Dalton's atomic theory that assumed atoms were indivisible. In order to account for the existence of the electrons, an entirely new atomic model was needed.
Explanation:
(1) IS THE BALANCED EQUATION AND REACTANT-> MG AND N2 AND PRODUCT ->MGN2.
(2) IS NOT BALANCED AND REACTANT->CF4 AND BR AND PRODUCT IS CBR4 AND F2
