Surface area: the larger surface area the quicker the reaction. Large particles have a small surface area in relation to their volume; fewer particles are exposed and available for collisions. This means less collisions and a slower reaction. The reaction rate is slower. However, small particles have a large surface area in relation to their volume; more particles are exposed and available for collisions. This means more collisions and a faster reaction. The reaction is faster.
Concentration: Increasing the concentration of the reactants will increase the frequency of collisions between the two reactants. So this is collision theory again. You also need to discuss kinetic theory in an experiment where you vary the concentration. Although you keep the temperature constant, kinetic theory is relevant. This is because the molecules in the reaction mixture have a range of energy levels. When collisions occur, they do not always result in a reaction. If the two colliding molecules have sufficient energy they will react.
Pressure: By reducing the volume in which the same amounts of particles exist the pressure is increased. Once the same numbers of particles are in a smaller area there is less space in which to move and so the particles are more likely to hit each other. It is therefore possible to predict that increasing the pressure will result in an increase in the rate of reaction. I will not test this variable because the school doesn't have the facilities to test it. However pressure is a continuous variable.
Hypothesis: I think that the greater the volume of HCL the quicker the reaction is going to be. But the surface area must be same. I think it is because the higher the concentration the more chance of all the particles colliding which makes a quicker reaction.
4). Apparatus: here is the list of equipment that I will need.
Connical flask (for mixing the chemicals).
Measuring beaker (For measuring the water and hydrochloric acid).
Pipette for measuring out the hydrochloric acid.
Stopwatch for timing the reaction.
Paper with visible cross.
Goggles for eye safety.
low concentration
High concentration
Reciprocal of conc.
Time
Fair test: I must Wash out the glassware with distilled water before use and between measurements. This was designed to prevent any other substance getting into the solution as this could damage the results.
-I must use a small measuring cylinder and funnel when measuring out hydrochloric acid, water, and sodium thisulphate rather than using beakers.
-I must also make sure I stay in the same place whilst the experiment just encase the readings change.
-I am going dry all the apparatus clearly so that the moist does not effect my reading.
-I am going to keep the temperature constant throughout by making sure nothing affects the temp in anyway.
-I must keep the same light for my reading to go right.
Safety: in order to make sure my investments use the following:
Glove to make sure that no chemical gets on my hands.
Apron so that chemicals don’t make contact with my clothes.
Extracting fan to take away all the fumes.
Method: first of all I am going to put a red cross under the connical flask. Then I will clean everything with distilled water and dry it. I will then put 10ml of HCL in the measuring cylinder just under 10ml then top it up with a pipette just to be exact. I will then poor the HCL in the connical flask with sodium thisulphate50ml while waiting with a stopwatch. I will then poor the HCL in the connical flask and as soon as they touch I will start the stopwatch. When the cross is not visible anymore I will stop the stopwatch. I will do the same but this time 40 ml of sodium thisulphate and 10ml of water. I will keep going down by 10 ml for sodium thisulphate and up 10 ml for water. After one reading I will note it down. I will clean the apparatus with distilled water and dry it then repeat the experiment two more times. I will then write down my results of all my readings.
