<span>Fill in the blanks: when an atom absorbs energy, the electrons move from their (ground) state to an (excited) state. when an atom emits energy, the electrons move from a(n) (excited) state to their (ground) state and give off (energy)</span>
When Cr dissolves in 1 M H₂Cr₂O₇
Cr(s) ⇄ Cr³⁺ + 3 e⁻
Cr₂O₇²⁻ + 14 H⁺ + 6 e⁻ ⇄ 2 Cr³⁺ + 7 H₂O
by multiplying the first equation by 2 and add the 2 equations;
The balanced redox reaction will be:
2 Cr(s) + Cr₂O₇²⁻(aq) + 14 H⁺(aq) → 4 Cr³⁺(aq) + 7 H₂O(l)
The reaction equation is:
Li + Br → LiBr
39 grams of Li = 39 / 7 = 5.57 moles of lithium
41.5 grams of Br = 41.5 / 80 = 0.52 mole of bromine