litmus paper

• Papel tratado com um corante natural que muda de cor conforme a acidez ou alcalinidade da substância, usado como teste químico simples para indicar se algo é ácido ou base. Também chamado de papel indicador.

A type of paper treated with a natural dye that changes color in response to acidic or alkaline conditions, used as a simple chemical test to determine whether a substance is an acid or a base.

1. Chemical test paperB2formal

   A type of paper treated with a natural dye that changes color in response to acidity or alkalinity, used to test pH levels.

   papel de tornassol

   • The chemist dipped the litmus paper into the solution to check its pH.
   • Blue litmus paper turns red in acidic conditions.
   • Litmus paper is a simple tool for determining whether a substance is an acid or a base.

2. Decisive indicatorC1informal

   A figurative term for a test or situation that reveals the true nature or outcome of something.

   papel de tornassol

   • The election results were a litmus paper for public opinion on the new policy.
   • His reaction to the criticism was a litmus paper of his character.
   • This project will be a litmus paper for the team's ability to work under pressure.