Question

is there two chemical liquids that make an endothermic reaction?

Answer 1

The baking soda (sodium bicarbonate) solution and citric acid solution.
The reaction is: H3C6H5O7(aq) + 3 NaHCO3(aq) --> 3 CO2(g) + 3 H2O(l) + Na3C6H5O7(aq)
An endothermic is a reaction that requires energy to proceed. The intake of energy may be observed as a decrease in temperature as the reaction proceeds. Once the reaction is complete, the temperature of the mixture will return to room temperature.