"Full of scorpions is my mind, dear wife" ↝ [a3s2]
Metaphor - scorpions represent evil as they inject poison into your body. Mirrors how Macbeth's mind is tainted by poisonous, damaging thoughts.
Metaphor depicts the power of his guilty conscience as it's constantly antagonising his thoughts.
"Will all great Neptune's ocean wash this blood clean from my hand?" ↝ [a2s2]
'great Neptune's ocean' - Hyperbolic language exemplifies the depth of Macbeth's guilt as he feels not even a God could save him.
'my hand?' - hypophora reveals Macbeth's acceptance of his guilt
His fixation on his hand may be symbolic of Macbeths being the architect of his own downfall.
"Out, out brief candle...full of sound & fury, signifying nothing" ↝ [a5s5]
Change in tone in this soliloquy evokes the impression that Macbeth has suddenly awoke from his stupor. His wife is dead, kingdom is falling apart & he's truly alone. His ambition & sacrifice has resulted to nothing.
'sound & fury' represents his violence & painful guilt which 'signifies nothing' as he has never accomplished anything everlasting. Macbeth acknowledges his ambition can't live on past his death & nor can his power. His crisis is caused by the undeniable truth of his own mortality.
"Out brief candle! Life's but a waking shadow, a poor player.... It is a tale" ↝ [a5s5]
'candle', 'shadow', 'player', 'tale' - nouns connote imitations and emptiness. Additionally, they are all delicate or temporary - Shakespeare suggests that everyone is insignificant, a mere candle flame compared to the light of the whole universe.