Question

1.If red litmus paper remains red after exposure to the sample AND blue litmus paper remains blue after exposure to the sample, then the sample is ? acidic , basic or neutral?

2. If a substance has juice in its name it will always be a good acid/base indicator.Is this statement TRUE or FALSE. Support your answer with evidence

3. When two acidic (or basic) solutions have the same solute and solvent, but different concentrations of solute their pH values will be, Identical or different?

4. Do all buffer solutions have to be composed of a weak acid and its conjugate base? Support your answer?

Answer 1

1. In acidic medium, blue litmus turns to red. But in basic medium red litmus turns to blue.

as , red litmus remains red and blue litmus remains blue in the sample, therefore the sample is neutral.

2. The statement is false. Juice are extracted from of natural liquid contained fruits are vegetables. many of them are indicators like red cabbage juice, but lime juice is not a indicator it is acidic.

3.

pH = - log [ H₃O⁺]

pH of solution depends on the conentration of hydronium ion ( mol/ L) . so different concentration gives different values of pH.

4.

No, all buffer solutions do not composed of weak acid and its conjugate base.

Buffer solution can resist the change of pH. buffer solution are two types , acid buffer and basic buffer. acid buffer is composed of weak acid and its conjugate base.

and basic buffer is composed of weak base and its conjugate acid ex. NH₄OH and NH₄Cl.