Rates of Reaction between Sodium Thiosulfate and Hydrochloric Acid

Question

I am doing a chemistry experiment investigating the rates of reaction between sodium thiosulfate and hydrochloric acid. Have been asked to make improvements to the temperature and concentration. Any ideas please

Answer 1

If we want to discuss temperature first, we know rates of reactions will increase as we increase the temperature. This is because the molecules are moving faster and faster. This leads to an increased number of molecules colliding and increased energy (which is required for a reaction to occur), so we get an increased rate of the reaction. This works as we decrease temperature as well. The molecules move slower, so less collisions, less energy, so slower reaction rate.

 

Talking about concentration, depending on the rate equation for Na2S2O3 and HCl, typically as we increase concentrations of reactants we will get an increased reaction rate because there is more compound to react with. If we decrease the amount of reactant we use, there's fewer molecules to interact so we will get a slower reaction rate.

 

This is exactly why reaction rate decreases with time. Because we're losing reactant concentration to product, so there's less to react, so the reaction rate slows.