In an isothermal reaction (either reversible or irreversible), DELTA T is constant..hence zero

Question

since temperature remains constant, can we also assume that heat is also zero?

if so, how then is an isothermal reaction different from an Adiabatic one?

Answer 1

Heat input is not necessarily zero in an isothermal process.

An example would be heating a gas and letting it expand enough to keep the temperature the same. This is one of the steps of a Carnot cycle engine.

Another example would be melting ice!