Skip to main content

GCSE chemistry--What does Weak Acid mean?

The strength of an acid or alkali depends on how ionised it is in water.


A strong acid or alkali is completely (100%) ionised. For hydrochloric acid

hydrogen chloride (in water) hydrogen ion + chloride ion
HCl(aq) H+(aq) + Cl-(aq)

All of the hydrogen chloride molecules
become hydrogen ions and chloride ions in water
(see examples for other strong acids).

For sodium hydroxide

sodium hydroxide (in water) sodium ion + hydroxide ion
NaOH(aq) Na+(aq) + OH-(aq)

Sodium hydroxide exists as ions both in water and in the solid.
(see examples for other strong alkalis).



A weak acid or alkali is only partly (less than 100%) ionised. For ethanoic acid

ethanoic acid (in water) hydrogen ion + ethanoic ion
CH3CO2H(aq) H+(aq) + CH3CO2-(aq)

Some of the ethanoic acid molecules become ions in water
but most of them stay as molecules.
The reaction is reversible (shown by the arrow).

For ammonia

ammonia + water ammonium ion + hydroxide ion
NH3(g) + H2O(l) NH4+(aq) + OH-(aq)

Some of the ammonia molecules become ions in water
but most of them stay as molecules.
Labels:

Comments

Post a Comment

Popular posts from this blog

The Missing Mail | Class IX - Interact in English

NCERT / CBSE Literature Reader for English Course (Communicative) Important Exercise Questions Q.3: (a) Why is Ramanujam worried about getting his daughter married? Give four reasons. (b) How does the postman console and guide Ramanujam and his family during each of the instances you have listed in 3 (a)? Ans 3(a): Ramanujam is worried as he could not find a suitable match to marry his daughter off which was getting delayed because of different reasons. The four causes of his worriedness are - (i) Sometimes horoscopes did not match, (ii) Sometimes the girl’s appearance were not approved, (iii) At times there were problems of too much dowry and other financial matters, (iv) The season was closing with only three more auspicious dates left, whereas, he was not able to finalise any alliance by that time. Ans 3(b): First instance - When Ramanujam said that horoscopes did not agree Thanappa consoled and guided him by saying that he should not utter inauspicious words and when the God wills ...
Post a Comment
Read more

The Tribute - Multiple Choice Questions

Question (1):   What does the word 'petite' mean? 1. strong 2. small 3. neat 4. clean Ans:   2 Question (2):   What was almost a routine affair for Babuli during his student days? 1. working in the city 2. writing to his elder brother 3. going home in the rickety bus 4. reading big books Ans:   3 Question (3):   What was written in the elder brother's letter? 1. That they were missing him in the village 2. That there was to be a partition 3. That there was a festival 4. That he would get money Ans:   2 Question (4):   How many days were left for the partition? 1. A week 2. A month 3. A day 4. Three days Ans:   1 Question (5):   How much money was expected for Babuli's land? 1. Seven thousand 2. Twenty thousand 3. Ten thousand 4. Forty thousand Ans:   2 Question (6):   What makes Babuli think of the butcher? 1. Hunger 2. Wife's heartlessness 3. The i...
Post a Comment
Read more

ENGLISH (Communicative) Sample Question Paper 5

Sample Paper – 2009 Class – XSubject – ENGLISH (Communicative) General instructions: The paper consist of FOUR sections: SECTION A (READING) - 20 Marks SECTION B (WRITING) - 30 Marks SECTION C (GRAMMAR) - 20 Marks SECTION D (LITERATURE) - 30 Marks Attempt all the questions. Do not write anything on the question paper. All the answers must be correctly numbered as in the question paper. And written in the answer sheets provided to you. Attempt all questions in each section before going on to the next section. Read each question carefully and follow the instructions. Strictly adhere to the word limit given with each question. Marks will be deducted for exceeding the word limit. SECTION A (READING) – 20 MARKS A1. Read the following passage and answer the following questions: [12] THE TUITION TRAP 1. Given the general awareness of the woeful condition of our State sch...
1 comment
Read more