indicators & neutralisation reactions

Question 1

methyl orange ph range?

Answer 1

3.1-4.4

Question 2

bromothymol blue?

Answer 2

6.0-7.6

Question 3

litmus

Answer 3

4.5-8.3

Question 4

phenolphthalein?

Answer 4

8.3-10.0

Question 5

how do indicators work?

Answer 5

indicators are weak acids/bases

–> changes in [H30+] will shift the equilibrium left/right hence changing colour

Question 6

application of neutralisation reaction in everyday life?

Answer 6

baking soda

HCO3 + Lactic Acid –> salt + co2 + h20

co2 –> helps dough rise and gives it a light texture

Antacid tablets:

CaCO3 , Mg(OH2) ; neutralise stomach acid (HCL) during acid reflux

Question 7

why do strong acids all have the same enthalpy value?

Answer 7

net ionic equation is always OH- + H3O+ –> 2H2O

Question 8

why do weak acids have a lower enthalpy value

Answer 8

only partially ionises in water, in an equilibrium reaction, so does not reach completion

Question 9

application of neutralisation reaction in an industrial setting?

Answer 9

sodium bicarbonate NaHCO3

• low price
• stability as a solid ( storage and transportation)

-weak nature

-amphiprotic nature