Presentation on theme: "Strength of Acids and Alkalis By SK Chan. Why do acids/alkalis show different properties? Acid/AlkalipH value Electrical conductivity 0.1 M Ethanoic acid4Low."— Presentation transcript:
Strength of Acids and Alkalis By SK Chan
Why do acids/alkalis show different properties? Acid/AlkalipH value Electrical conductivity 0.1 M Ethanoic acid4Low 0.1 M Hydrochloric acid 1High 0.1 M aqueous ammonia 9Low 0.1 M sodium hydroxide 13high
What happens when weak acid is dissolved in water?
Weak acid Only slightly ionized in water to give aqueous hydrogen ions, H + (aq). It is found that about 1% of 0.1 M ethanoic acid molecule is ionized in water. CH 3 COOH(aq) CH 3 COO - (aq) + H + (aq)
How about Strong acid? An acid that is completely ionized in water to give hydrogen ions, H + (aq). HCl(aq) H + (aq) + Cl - (aq) 0.1 M 0 M 0 M (before ionization) 0 M 0.1M 0.1M (after ionization)
Question 1 Suggest 3 different properties to distinguish: 0.1 M H 2 SO 4 and 0.1M CH 3 COOH
Three different properties pH Rate of reaction with metals, carbonates, etc. Conductivity
Check point What is the term used to describe the formation of hydrogen ions from acid molecule? Explain in your word the definition of weak acid. Name one weak and one strong acid. Suggest methods to distinguish weak acid from strong acids.
Difference between Strength and Concentration Strength degree of ionization Concentration quantity of acids in unit volume 10M Ethanoic acid 10M Hydrochloric acid How are they differ from each other?
Question 2 Which of the following has a lower pH? A 0.1 M hydrochloric acid B 0.1 M ethanoic acid C 0.1 M sulphuric acid D 0.1 M nitric acid Ans. C
Question 3 Which of the following solutions has the HIGHEST concentration of hydrogen ions? A 20 cm 3 of 2M sulphuric acid B 100 cm 3 of 0.2 M hydrochloric acid C 100 cm 3 of 4M ethanoic acid D 100 cm 3 of 2M sodium hydroxide Ans. A
Reading Assignment Find the names and formula of two weak alkalis. Describe and explain three different methods to distinguish them from strong alkalis.