Dmitron1036:
Ds18b20?
Yes, save yourself some trouble, and replace the LM35 for a DS18B20 digital temp sensor.
Best to use a logic level mosfet to switch the heating element on/off.
A relay(module) would put an extra load (heat) on Arduino's 5volt regulator.
First diagram on this page could work.
Replace the "motor" in the diagram for your heating element, and you could omit the diode.
Leo..