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Chemistry is one of the physical Sciences
CHEMISTRY - Secondary 1
In This part we will study
Measurement in chemistry
Measurement: It is the comparison of an unknown quantity with another quantity of the same kind in order to know the number of times which the first includes the second .
Any measuring process must include two main points, which are :
 Numerical value: describes the measured quantity or property.
 Suitable measuring unit: indicates a certain standard to which the measured quantity is being referred

Example :
When we say that the length of the football playing field is 100 yd.
We mean that the field is 100 times longer than the standard length which is called Yard (yd).

The importance of measurement is clearly obvious, as follows :
 Giving information about the type and the concentration of elements forming the substance :
Nutrition facts labels are very important for the consumer, as it enables him to be aware of the types and the concentrations of the components.

Application :
Measuring the concentrations of the ions which form the salts in mineral water.

* By analyzing the data on the labels of each of the two bottles, the following can be concluded :
The consumer who follows low salt diet is preferred to use bottle (A) , where it contains lower amounts of ions forming the salts.
• The person who consume 1.5 L of water of bottle (B) during one day, he will receive an amount of calcium ions Ca2+ equals 70 x 1.5 = 105 mg


 Monitoring and health protection.
Environmental safety and health protection requires monitoring each of the following :
1. The validity of drinking water for human use.
2. The purity of air.
3. Safety of food and agricultural products.

Application :
Monitoring the validity of drinking water for human use according to international standards.
* The table shows the international standards to evaluate the validity of drinking water, and according to these standards, the bottles (A) and (B) are both valid for human use, as the concentrations of the ions in both of them are within the safety range.

 Diagnosis and suggesting the suitable medication in case of defects (diseases).
Medical analysis reports indicate the health status of patients referring to medical analysis values of healthy persons which are known as :
The reference value: which is the normal limits of lowest and highest values obtained on normal healthy people.

Application :
*Using the opposite medical analysis report to clarify the following :
- The glucose level in this person's blood is within normal range.
- The amount of uric acid is abnormal, it is higher than the normal reference value range.
- This indicates the presence of a certain malfunction in this person's body.


Best wishes to you
Mr.Ahmed Elbasha

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شرح كيمياء لغات اولي ثانوي - مستر احمد الباشا