to change into; to transform into — to become something else or turn into another state (often used as ～に化する).
気体が冷えて液体に化する。
The gas cools and changes into a liquid.
怒りが悲しみに化することもある。
Sometimes anger turns into sadness.
彼の言葉はやがて噂に化して町中に広がった。
His words eventually turned into a rumor and spread throughout the town.
to influence; to manifest as an effect — to appear or act as an influence or effect on something.
政策の失敗が消費行動に化して経済に響いた。
The failure of the policy manifested in consumer behavior and affected the economy.
その事件は市民の心情に化して選挙結果に影響を与えた。
That incident influenced public sentiment and affected the election results.
彼女の存在がチームの雰囲気に化して、皆の士気が上がった。
Her presence influenced the team's mood, raising everyone's morale.