11. In a neutral solution,
A the [OH–] is less than the [H+]
B the [OH–] is more than the [H+]
C the [H+] is equal to 10-7 M
D the [OH–] is more than 10-7 M
E the pH is higher than 7
12. A weak base
A can have a pH of maximum 7.5
B does not dissolve in water
C reacts with only weak acids
D dissolves in water, but does not dissociate to ions
E is a weak electrolyte
13. What is the pH of a wine that has the [OH–] of 10-11 M?
A 11
B -11
C 3
D -3
E 7
14. Which of the following terms describes the best a substance which is produced from a base by accepting an H+?
A conjugate base
B Arrhenius base
C conjugate acid
D a weak electrolyte
E Bronsted base
15. Given the following Ka values, determine which row contains the substances in order of increasing acid strength.
H3PO4 Ka = 7.5 x 10-3
HCN Ka = 6.2 x 10-10
HF Ka = 6.5 x 10-4
A H3PO4, HF, HCN, H2SO4
B H2SO4, H3PO4, HF, HCN
C H2SO4, HCN, HF, H3PO4
D HCN, HF, H3PO4, H2SO4
E HCN, HF, H2SO4, H3PO4
answer and explain please
chemistry questions help please?
2018-01-03 9:14 pm
回答 (2)
2018-01-03 10:07 pm
✔ 最佳答案
11. The answer: C the [H⁺] is equal to 10⁻⁷ M
It is defined that a solution at 25°C is neutral when [OH⁻] = [H⁺] = 7, acidic when [OH⁻] < [H⁺], and basic when [OH⁻] > [H⁺].
====
12.
The answer: E is a weak electrolyte
A is false. The pH of a base A should be less than 7.
B is false. A weak base dissolves in water.
C. is false. A weak base can react with all acids.
D is false. A weak base dissolves in water and then incompletely dissociates in water.
E is true. A weak base incompletely dissociates in water, and thus it is a weak electrolyte.
====
13.
The answer: C 3
pOH = -log[OH⁻[ = -log(10⁻¹¹) = 11
pH = pKw - pOH = 14 - 11 = 3
====
14.
The answer: C conjugate acid
Base + H⁺ ⇌ conjugate acid
====
15.
The answer: B H₂SO₄, H₃PO₄, HF, HCN
H₂SO₄ is a strong acid, while the other three acids are weak. Hence, H₂SO₄ is the strongest acid among the 4 given acids.
The higher the Ka value, the stronger the acid is.
Ka value: H₃PO₄ > HF > HCN
Hence, acid strength: H₃PO₄ > HF > HCN
2018-01-03 9:30 pm
11. C the [H+] is equal to 10-7 M
12. E is a weak electrolyte
13. C 3
14. C conjugate acid
15. B H2SO4, H3PO4, HF, HCN even though the Ka for H2SO4 wasn't given. It is a strong acid.
12. E is a weak electrolyte
13. C 3
14. C conjugate acid
15. B H2SO4, H3PO4, HF, HCN even though the Ka for H2SO4 wasn't given. It is a strong acid.
收錄日期: 2021-04-18 18:01:47
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20180103131402AAPjOjh