1. pH Scale pH 4. סקלת ה- The pH of a solution
is used to indicate the acidity of a solution.
has values that range from 0 to 14 representing the H3O+ concentration of a solution.
is acidic when the values are less than 7.
is neutral with a pH of 7.
is basic when the values are greater than 7.

2. תמיסה חומצית, ניטרלית ובסיסית נקבעת עפ"י pHערך ה
Acidic solution pH < 7.0 [H3O+] > 1.0 x 10-7 M Neutral solution pH = 7.0 [H3O+] = 1.0 x 10-7 M Basic solution pH > 7.0 [H3O+] < 1.0 x 10-7 M

3. דוגמאות מחיי היום יום עם ערכי חומציות שונים

4. בנוזלי הגוף pHערכי ה- Blood 7.4 Pure water 7.0 pH H+ conc [M]
Gastric Juice
1 - 2
to 10-2
Coca cola 3
10-3
Urine
5-8
10-5 to 10-8
Saliva
6.4
4 x 10-7
Blood
7.4
4 x10-8
Pure water
7.0
10-7
לא בנוזלי הגוף

5. pHאמצעים ושיטות למדידת ה-
pH can be measured using
a pH meter.
pH papers that turn specific colors when placed in
solutions of different pH values.
indicators that change color with changes in pH.

6. Litmus Paper נייר לקמוס
Copyright © 2007 Pearson Benjamin Cummings. All rights reserved.

7. pHנייר
pH Paper pH pH

8. Paper or plastic strips that contain combinations of indicators estimate the pH of a solution by simply dipping a piece of pH paper into it and comparing the resulting color with standards printed on the container
Copyright © 2007 Pearson Benjamin Cummings. All rights reserved.

9. Red Cabbage Indicator
Copyright © 2007 Pearson Benjamin Cummings. All rights reserved.

10. Phenolphthalein Indicator
Colorless = Acidic pH
Pink = Basic pH

11. תרגיל
Learning Check
Identify each solution as acidic, basic, or neutral.
___ A. HCl with a pH = 1.5
___ B. pancreatic fluid [H3O+] = 1 x 10−8 M
___ C. Sprite soft drink, pH = 3.0
___ D. pH = 7.0
___ E. [OH−] = 3 x 10−10 M
___ F. [H3O+ ] = 5 x 10−12 M

12. Solution פתרון Identify each solution as acidic, basic, or neutral.
Acidic A. HCl with a pH = 1.5
Basic B. Pancreatic fluid [H3O+] = 1 x 10−8 M
Acidic C. Sprite soft drink pH = 3.0
Neutral D. pH = 7.0
Acidic E. [OH−] = 3 x 10−10 M
Basic F. [H3O+] = 5 x 10−12

13. pHחישוב ה- pH is the negative logarithm (base 10) of the [H3O+] .
For a solution with [H3O+] = 1 x 10−4 M:

14. pH ל- [H3O+] הקשר בין ערכי ה-
pOH *כפי שרואים בטבלה, ישנה גם סקלת

15. במחשבון pHחישוב ה-
חישובים

16. Calculate pH from [H3O+]
Find the pH of a solution with a [H3O+] of 1.7 x 10−3 M.
Step 1 Enter the [H3O+].
Enter 1.7, then press EE or EXP. Enter 3, and then −/+ to change the sign.
1.7−03 or 1.7−03 or 1.7E−03
Step 2 Press log key and change the sign. log −/+
Calculator Display

17. המשך Find the pH of a solution with a [H3O+] of 1.7 x 10−3 M.
Step 3 Adjust the number of SFs on the right of the
decimal point to equal the SFs in the
coefficient.
2 SF

18. Learning Check תרגיל 1 A. pH = 9.0 B. pH = 7.0 C. pH = 5.0
What is the pH of coffee if the [H3O+] is 1 x 10−5 M?
A. pH = 9.0
B. pH = 7.0
C. pH = 5.0

19. Solution פתרון 1 What is the pH of coffee if the [H3O+] is 1 x 10−5 M?
Step 1 Enter the [H3O+].
Enter 1, then press EE or EXP . Enter 5, and then −/+ to change the sign.
1−05 or 1−05 or 1E−05
Step 2 Press the log key and change the sign.
Calculator Display

20. המשך פתרון What is the pH of coffee if the [H3O+] is 1 x 10−5 M?
Step 3 Adjust the number of SFs on the right of the
decimal point to equal the SFs in the
coefficient.
Answer is C.
1 SF

21. תרגיל 2
Learning Check
The [H3O+] of tomato juice is 2 x 10−4 M. What is the pH of the solution?
A. 4.0
B. 3.7
C. 10.3

22. Solution פתרון 2 The [H3O+] of tomato juice is 2 x 10−4 M.
פתרון 2
Solution
The [H3O+] of tomato juice is 2 x 10−4 M.
Step 1 Enter the [H3O+].
Enter 2, then press EE or EXP . Enter 4, and then −/+ to change the sign.
2.0 EE or EXP 4 −/+ = 2−4 or 2−4 or 1E−4
Step 2 Press the log key and change the sign.
Calculator Display
Calculator Display

23. Solution המשך פתרון 2 The [H3O+] of tomato juice is 2 x 10−4 M.
המשך פתרון 2
Solution
The [H3O+] of tomato juice is 2 x 10−4 M.
Step 3 Adjust the number of SFs on the right of the
decimal point to equal the SFs in the
coefficient.
Answer is B.
1 SF

24. תרגיל 3
Learning Check
The [OH−] of a solution is 1.0 x 10−3 M. What is the pH? A B
C. –11.00

25. פתרון 3
Solution
The [OH−] of a solution is 1.0 x 10−3 M. What is the pH?
Step 1 Enter the [H3O+].
Because [OH−] is given for the ammonia solution, we need to calculate [H3O+]. We use the ion
product constant of water, Kw , to obtain [H3O+].
Calculator display

26. המשך פתרון 3 The [OH−] of a solution is 1.0 x 10−3 M. What is the pH?
Step 2 Press the log key and change the sign. log −/+
Step 3 Adjust the number of SFs to the right of the
decimal point to equal the SFs in the coefficient.
Answer is B.
Calculator display

27. pH מתוך ה [H3O+]חישוב ה-

28. pH מתוך ה [H3O+]דוגמא לחישוב ה-
Calculate the [H3O+] for a pH value of 8.25.
Step 1 Enter the pH value and change the sign.
Enter –/ –8.25
Step 2 Convert –pH to concentration.
Press the 2nd function key and then the 10x key.
2nd x
−09 or −09 or E−09
Or, press the inverse key and then the log key.
inv log
Calculator display
Calculator display

29. המשך Calculate the [H3O+] for a pH value of 8.25.
Step 3 Adjust the SFs in the coefficient.
2 SF

30. תרגיל
Learning Check
What is the [H3O+] of a solution with a pH of 11.2?
A. 6 x 10−12 M
B x 10−12 M
C x 10−12 M

31. Solution פתרון What is the [H3O+] of a solution with a pH of 11.2?
Step 1 Enter the pH value and change the sign.
Enter 11.2 –/ –11.2
Step 2 Convert –pH to concentration.
Press the 2nd function key and then the 10x key.
2nd x
−12 or −12 or E−12
Or press the inverse key, and then the log key.
inv log
Calculator display
Calculator display

32. Solution What is the [H3O+] of a solution with a pH of 11.2?
Step 3 Adjust the SFs in the coefficient.
1 SF