Prediction And Theory Why
I predict that the higher the concentration the quicker the reaction will be. The collision theory says Particles are always moving around, in order for a reaction to occur, the particles have to collide with enough force. If there is not enough energy it will only make the particles bounce off each other. If solutions of reacting particles are made more concentrated there are more particles per unit volume. Collisions between reacting particles are therefore more likely to occur.
Equipment
In order to do this experiment, I will need certain experiment, using my preliminary experiments I decided on using the following apparatus:
3 Measuring cylinders: 1 to measure the water
1 to measure the Hydrochloric Acid
1 to measure the Sodium Thiosulphate
Conical Flask: This is where both Sodium Thiosulphate and Hydrochloric Acid
are going to be mixed
Timer: This is to measure how long it will take for the x to disappear
Paper with a cross-marked on it: This is going to be under the Conical Flask
Goggles: This to protect my eyes so that no substances will come into contact
with them
Method
Firstly I will measure the right amount of Sodium Thiosulphate at 10cm3, Hydrochloric acid (varying Concentrations), and Water into three separate measuring cylinders. The Sodium Thiosulphate will be poured in to the Conical Flask. Then I will add the water with the Hydrochloric Acid this will make up the different concentrations I decided to use. Then I will pour the Hydrochloric Acid will be poured into the flask where the Sodium Thiosulphate is. From the moment the Hydrochloric Acid and Sodium Thiosulphate come in to contact I will begin the timer and measure the time how long it takes for the solution to go cloudy enough so that the paper underneath the flask with the black cross disappears I will stop the timer and record these. For each concentration it will be repeated 3 times. The whole procedure is then repeated. I will then put these results in a table, I will work out the averages and then draw a graph.
Safety
In my experiment I will try to carry out the experiment as safely as possible. This will include:
No running – I will be very careful when doing my experiment. I will be calm and take my time. I will not run because I could fall over, hurt myself, spill chemicals and break glassware.
Wipe up spills –If I spill something I will clean it up quickly and appropriately. If I don’t someone could slip on chemicals, and hurt themselves. If skin gets in to contact with chemicals it could burn.
Wear goggles – as I am using concentrated hydrochloric acid I will wear goggles at all times so that any chemicals doesn’t come in to contact with my eyes because it could blind me.
Acids are corrosive – This is basically the same as wiping up spills but this also involves carrying and handling the chemicals. I am going to Be careful not to get it onto my skin.
Wash Hands – After the experiment I will wash my hands so that I have
Washed any acid that I have touched when doing the
experiment
Wear Apron – I will wear a apron so that my clothes are tucked away and no
chemicals will have no contact with them
Table Of Results
Graph
Analysis- Considering Evidence
The experiments made were very successful and I had managed to complete the experiment fully and fairly. In this experiment I found out that as the concentration increases the time taken for the reaction to take place decreases. This supports my prediction and the particle theory that if solutions of reacting particles are made more concentrated there are more particles per unit volume. Collisions between reacting particles are therefore more likely to occur. Looking at my table of results the fastest reaction made was with no water (50cm3 Hydrochloric Acid) the average time for this reaction was 95 seconds. The slowest reaction made was the with 50cm3 water and no Hydrochloric Acid this reaction time was endless, the colour didn’t change at all, this is because there was no hydrochloric acid present only water and Sodium Thiosulphate what happened was it changed the Sodium Thiosulphate concentration so no reaction took place. I have noticed that there is a pattern.
Evaluation
I think that this investigation went very well and that I carried this experiment to the best of my abilities. My range of 5 concentrations has been enough to plot a graph with a line of best fit and a table of results, which supports my prediction that the higher the concentration of Hydrochloric Acid the quicker the rate of reaction. My graph and table of results are reasonably are quite accurate and is quite reliable.
The experiments were done fairly but it could have been even fairer. Because the reaction for each experiment was finished when the black cross on the paper underneath conical flask disappeared this is only seen by the eye. When doing the experiment we had trouble deciding when the black cross-had disappeared because everyone in the group had different eye types, this meant that this experiment wasn’t entirely fair in the experiment. To solve this problem we could use a devise called a light dependent resistor. This devise will be fixed in an electrical circuit with an ammeter. The resistor will be placed underneath the flask on top of the x. we can take a trial test and when both the Hydrochloric Acid and Sodium Thiosulphate are added and the x cannot be seen, we can record these results and use these for the testing. This circuit will be used for each test and when the ammeter shows that reading from the trial, stop the timer. This device will give us more accurate and more reliable than my group deciding when the x has disappeared.
