Temperature has an effect on most all chemical reactions.
HCl Is a gas dissolved in water, the higher temperature can make the reaction more reactive, possibly because molecules move more and are more reactive? as the temperature rises it can evaporate water making the acid more concentrated (where most reactions can become more reactive), and where unused free HCl in the diluted solution concentrates...
With HCl, we also normally use oxidizers or other gasses like oxygen, cold solutions hold gasses, hot solutions evolve gas (the gas leaves the solution) so heat can drive off gas from solution, but at the same time make the reaction more vigorous or go faster, so we have temperatures driving away gases we need in solution at the same time makes the solution more reactive. a double edge sword.
Temperature can drive off a gas from a solution, different gasses have different volatilities, some can be driven from solution with heat, oxygen gas is more volatile than HCl gas, so we can drive oxygen from HCl acid concentrating the HCl acid while removing most of the dissolved oxygen in the solution. or we can heat a solution of aqua regia and vaporize off the nitric acid from the HCl as we concentrate the free acid in solution, nitric is more volatile than HCl gas so under the heat of evaporation the nitric becomes a gas easier than the HCl and can be driven off with heat.
With some metals and acids in some reactions, the more the acid is concentrated, it can slow down the reaction, the reaction will go faster in a more diluted acid where water is beneficial to converting gasses back into acid, where a more concentrated acid passivates the metal forming an oxide coating slowing the reaction of attacking the metal, silver in concentrated nitric can passivate making it hard to dissolve, or much slower than the reaction would be in a dilute acid. you may also see the reaction may be slow at first and then proceed with a vengeance after the acid begins to break down and weaken while producing heat in the reaction the oxide layer is broken and the reaction takes off.
A temperature is a tool of the trade, we need to learn to use these tools to our advantage.
