شرح ساينس الصف الثالث الاعدادي لغات
شرح ساينس 3 اعدادي
لينك تحميل الملزمة
https://drive.google.com/file/d/1F3N85wNYA_Jgr9dma4aBgky0o3gn2hgH/view?usp=sharing
لينك تليجرام
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In This Video :
Activity (1): The effect of surface area on the speed of the chemical reaction:
Observation:
The rate of reaction of hydrochloric acid with iron filings is faster than that in case of a piece of iron.
Explanation:
The surface area of iron filings exposed to reaction with the acid is more than the surface area of the iron piece, so the reaction in case of iron filings ends in a short time than that in case of iron piece.
Conclusion:
The speed of chemical reaction increases by increasing the surface area of the reactants exposed to reaction.
2. The concentration of the reaction
You may have noticed that :
The probability of collisions between persons in crowded street is bigger than that in a quiet street.
Similarly; When the concentration (no. of molecules) of the reactants increases, the number of probable collisions between molecules increases, thus the speed of chemical reaction increases.
Activity (2): The effect of reactants concentration on the speed of the chemical reaction:
Observations:
1. The amount of the evolved bubbles in case of using cone. hydrochloric acid is more than that in case of dil. hydrochloric acid.
2. The rate of the reaction of magnesium ribbon with cone. hydrochloric acid is faster than that in case of dil. hydrochloric acid.
Explanation:
The number of molecules of acid in concentrated solution is more than that in its diluted solution, which leads to increasing the number of probable collisions between reactant molecules, so the speed of chemical reaction increases.
Conclusion:
The speed of chemical reaction increases by increasing the concentration of the reactants.
Combustion of the steel scourers used for cleaning aluminium pots in a jar filled with pure oxygen is faster than its combustion in atmospheric air.
Due to increasing the speed of chemical reaction by increasing the concentration of oxygen gas.
3. The Temperature of the reaction
On increasing the temperature of the reactants, the speed of the reactants molecules increases, so the number of probable collisions between them increases, so the speed of the chemical reaction increases.
Activity (3): The effect of temperature on the speed of the chemical reaction:
Observation:
The effervescence happens in case of hot water is faster than that in case of cold water.
Explanation:
The speed of the reactant molecules in case of hot water is greater than that its speed in case of cold water, which leads to increasing the number of probable collisions between molecules, so the speed of the chemical reaction increases .
Conclusion:
The speed of chemical reaction increases by increasing the temperature of the reaction.
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