Science Investigation- Changing Temperatures

SCIENCE INVESTIGATION- CHANGING TEMPERATURES

Aim: 

To design and carry out an experiment to investigate a factor which could affect the temperature rise when a metal reacts with a copper sulphate.

Research question: What would affect the temperature rise of an exothermic reaction?

Dependant variables- Change in temperature

Independent variables- The mass of magnesium fillings added

Controlled variables- The volume and concentration of copper sulphate

Introduction: 

Displacement reaction occurs in a metal salt solution in which the metal will displace a less reactive metal. In this investigation I choose to use Magnesium to react with copper sulphate solution. Magnesium is a more reactive metal than copper. The atoms of the reactive Magnesium give away electrons and the ions of the less reactive copper are forced to accept these electrons.

Preliminary Experiment:[pic 1]

When mixing Magnesium powder and copper sulphate solution together, a displacement reaction occurs. The Magnesium replaces the copper and becomes Magnesium sulphate:

Magnesium + Copper Sulphate → Copper + Magnesium Sulphate

This will result in an exothermic reaction. An exothermic reaction is one which gives out energy (usually heat) and shown in the rise of temperature. [pic 2][pic 3]

Prediction:

My prediction for this investigation is that the greater amount of magnesium powder added to the solution, the greater the temperature rise. A displacement reaction will take place between the magnesium and the copper. According to the reactivity series, magnesium is more reactive than copper, and a more reactive metal will displace a less reactive metal from its compound. The temperature will double when the mass of magnesium powder is doubled, this is because there will be more Magnesium and copper atoms colliding with each other, forming more bonds and so more heat will be given off.

However, there will be a point where the change in temperature will be about the same as it was with the previous mass of magnesium fillings, as there will not be enough copper molecules to react with the magnesium.

0.1g is the minimum mass the electronic scale could read. I will start my mass of magnesium fillings at 0.2g as I think 0.1g will not show much change in temperature. I will double this 5 times which brings me 5 readings: 0.2g, 0.4g, 0.8g, 1.6g, and 3.2g.[pic 4][pic 5]

Apparatus:

• 5 boiling tubes
• A thermometer
• A boiling tube rack
• A measuring cylinder
• A spatula
• A stopwatch
• An electronic scale
• 2 beakers
• Stand & Clamp

Materials:

• 50ml of 0.5M copper sulphate solution
• 6.5g/15 pieces of magnesium fillings

Method:

1. Collect all the apparatus listed above and place them neatly on the table.
2. Place 5 boiling tubes in the rack. Measure 10ml of copper sulphate solution and pour it into each tube.
3. Measure out the different masses of Magnesium powder using the electronic scale, beaker and the spatula.
4. Measure the starting temperature of the copper sulphate solution.
5. Add the first mass of Magnesium power into one of the copper sulphate solution. Start timing. Stir the solution with a glass rod.
6. Check the temperature and record it every minute. Stop the timer after 5 minutes.
7. Repeat this for the next four masses of Magnesium powder.
8. Repeat the whole experiment again.

Since no magnesium powder is provided (only magnesium ribbon available), the unit is changed to pieces 

Results table: