Chemistry investigation

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Omrit Sarangi                


Aim: I am going to carry out an investigation measuring the rate of reaction between hydrochloric acid and magnesium. The independent variable will be the molar of the hydrochloric acid; I will be diluting it with water to change the concentration. The dependent variable could be one of four things; Temperature change, Mass loss, Gas produced using a burette or gas produced using a gas syringe. The dependent variable of the primary experiment will be decided once I have performed four preliminary experiments each with the different dependent variables. The results of these preliminaries will help me determine which factor is the most accurate to measure.

Background Information: As I am planning to investigate the rate of reaction by changing the concentration of the acid I should take into consideration how the reaction is affected by concentration.

If there is more of a substance in a system, there is a greater chance that molecules will collide and speed up the rate of the reaction. If there is less of something, there will be fewer collisions and the reaction will probably happen at a slower speed.

As you increase the concentration of the acid, there are more acid particles in the same volume. Therefore there is a greater chance of acid particles colliding, and reacting, with particles on the surface area of the magnesium ribbon.

Here is an example of how the rate of reaction will increase if the concentration gets higher:

With this in mind it is clear to see that as I decrease the concentrate of the acid by adding water to it I will be decreasing the rate of reaction. There is a positive correlation between the two variables.

The experiment equation that will effectively happen is:


Mg     +         2HCl ---- MgCl2 + H2

Magnesium; Magnesium is a light, silvery-white, and fairly tough metal. It tarnishes slightly in air, and finely divided magnesium readily ignites upon heating in air and burns with a dazzling white flame. Because serious fires can occur, great care should be taken in handling magnesium metal, especially in the finely divided state. Water should not be used on burning magnesium or on magnesium fires.

Hydrochloric acid; Hydrochloric acid is the aqueous solution of hydrogen chloride gas (HCl). It is a strong acid, the major component of gastric acid, and of wide industrial use. Hydrochloric acid must be handled with appropriate safety precautions because it is a highly corrosive liquid.

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Hydrogen; when mixed with oxygen across a wide range of proportions, hydrogen explodes upon ignition. Hydrogen burns violently in air. It ignites automatically at a temperature of 560. Another characteristic of hydrogen fires is that the flames tend to ascend rapidly with the gas in air.

Magnesium chloride; this is the name for the chemical compounds with the formulas MgCl2 and its various hydrates MgCl2 (H2O) x. These salts are typical ionic halides, being highly soluble in water. The hydrated magnesium chloride can be extracted from brine or sea water. Anhydrous magnesium chloride is the principal precursor to ...

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