How Does the Concentration of the Sodium Thiosulfate Affect the Rate of Reaction to Hydrochloric Acid?

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How does the concentration of the sodium thiosulfate affect the rate of reaction to hydrochloric acid?


page 1: contents, aim, prediction, equation, diagram
page 2: equipment, preliminary experiments
page 3:
page 4:
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In my investigation I am trying to find out how the rate of reaction between sodium thiosulfate and hydrochloric acid gets affected but the concentration of the thiosulfate.

My prediction is that the increased concentration of the thiosulfate will in turn lead to an increase in the rate of reaction. This is a well informed prediction as I know that one of the factors that speeds up rates of reaction is the increasing of the substrate, this increases the amount of particles that the hydrochloric acid can react with meaning that the reaction will go faster.

Equation of the reaction:

2HCl + Na2S2O3 --> 2NaCl + SO2 + S + H2O
Factors that affect the experiment:
The main factors that affect the experiment are
The concentration of hydrochloric acid
The concentration of sodium thiosulfate
The time in which the experiment happens in
However, there are still some less important factors that could affect the results, such as: Temperature
Human error or human interference

These factors will affect the experiment if I don’t do anything to control them. There are many ways in which I will control them I will control the concentration’s of both hydrochloric acid and sodium thiosulfate, by making a definite measurement each time, i will have the right concentrations of thiosulfate and have the right measurement of hydrochloric acid. Another way in which I will maximize accuracy and precision of my measurements is that I will use equipment with small measurements such as mm, this allows for a more accurate reading. I will control the time that the experiment runs for by having a good stopwatch that instantly stops/starts the time when I click it to minimize human error. I will control temperature by keeping thermometers around so that the temperature can be monitored and changed if necessary The final and hardest to control factor is the element of human error or human interference. This factor is very hard to adjust because if is very rare not to make mistakes. In order to minimize the chance that me or someone else could knock over my experiment I have made it very close together on the desk instead of all spread out making it easier to see. Another thing I will try to help make less errors is to double check every measurement that I make which should discount human error. Equipment Diagram:

Reason: to protect my eyes against potential danger as hydro chloric acid is harmful and corrosive Why: I chose goggles because they cover a large precent of the investigators face and eyes and the school provides them for safety precautions. Pen and paper

Reason: To write down the cross on the piece of paper so I can see when it disappears and the experiment finishes Why: This was one of the only things I could do to measure the time in which the flash gets fully translucent. Pipette

Reason: To measure out the volumes of liquids and to accurately move them to where they need to be. Why: The pipette has very small markers on it and this makes it have a very high accuracy. Measuring cylinder

Reason: This was also to measure.
Why: I used the measuring cylinder because it was big enough to hold anything I needed and was the only thing available. Stopwatch:
Reason: This is needed because I am timing my experiment.
Why: It was either a clock or this, and I am certain that this is more accurate. Conical flask:
Reason: To hold my experiment / where my experiment actually takes place Why: A conical flask can be swirled with the mixture in, whereas in a normal beaker the water would just splash out Preliminary experiments:

My preliminary experiments helped the real experiment become the most...
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